67-72 frame conversion for 63 Knee Knocker Cab and Bed

[SCOTI]

Originally Posted by jmcdaniel

thx scoti, that answers my question about the frame horns. i have one of the outer brackets from the 63 bumper which i hope will help in possible positioning. also, do you think it would be just as easy to make a core support cross member. i don't remember what the 60-66 crossmembers looked like. if it is a straight piece of steel i think it might be cheaper and just as effective to build one. your opinion?

That's what I have in mind for mine. I'll have a better idea once the front clip is in place.

[66-PMD-GMC]

As far as the Radiator support/cross member is concerned, I would think if someone was going to retrofit a cross flow or other style radiator in the truck it would make sense to fab up something that would work better with what they are doing.
I am going with a stock style radiator and will be utilizing the bottom radiator brackets that bolt to the cross member. In my case it makes sense to swap the original stuff.
As far as the frame horns go. The bumper support brackets are not what is being referred to as frame horns here. The frame horns are the front sections of the frame proper that the bumper bolts to. This is what is being reffered to as the "horns" of the frame. The bumper support brackets are just brackets and need no modification other than being placed and bolted in.

[66-PMD-GMC]

apparently.... one should never leave a bare frame in one's driveway overnight as it seems it is obvious now that they are easy to carry away silently....
Freaking jerkwad thieves!

[chad64chevy]

do what!? someone stole your frame??

[SCOTI]

Someone wanted a swb frame or scrap guys saw opportunity for $$. Sux either way....

[66-PMD-GMC]

I needed room on my side yard so I rolled the 69 frame out of the way and into the driveway with a floor jack.
NEVER had a problem before with anything disappearing.
Got up at 4:30am, made coffee, walked outside and had my whole day ruined.
Called every scrap place within 50 miles.
CRAP!

[66-PMD-GMC]

Well, the 69 frame is gone and I still have the 63 SWB frame.
Now that the pain has subsided and my brain is working I am wondering if I had a drivers side frame horn from a 67-72 frame, how hard would it be to graft in the power steering box notch and mounting holes??
I have been looking for another frame since Friday but only find LWB frames.
Anyone done this?

[66-PMD-GMC]

Have a line on a frame horn, picking it up tomorrow.
Guess it is the next best thing.

[SCOTI]

Originally Posted by 66-PMD-GMC

Have a line on a frame horn, picking it up tomorrow.
Guess it is the next best thing.

Sounds like a good alternative.

[66-PMD-GMC]

Originally Posted by SCOTI

Sounds like a good alternative.

I have found a couple frames this morning that are sky high priced. The sellers must be smokin' something.
My intent was to do a blow by blow pictorial conversion build. If I find someone who has a reasonably priced stripped frame I will resume the build.
I need no trick suspension, powder coating, "bag" system or otherwise.
I have all the parts that I need and more. I just need that frame.
If I don't find a frame I will have my son help me and I will graft in the frame section needed for power steering and save the frame conversion for later.
I see posts for how to information here so often that I thought sharing my limited fabrication skills might help someone.

[66-PMD-GMC]

Got a 69-72 frame horn and wire brushed it bare, threw a splash of layout die on it and started scribing cut lines.
Saturday I will have my son take some photos when I trim everything up with a die grinder.
Once that is done I'll start on the 63 frame horn getting it ready for the graft.

[66-PMD-GMC]

Update-
Frame graft is coming along well. The 72 frame horn is getting a good work over.
I took a before photo. It is very close to being ready for the graft.
Haven't had a lot of time to work on the trucks.
I will still try and find another frame to do the conversion.
I have prints drawn and will prove out the dimensions during the conversion.

[66-PMD-GMC]

Update-
I have a 72 frame (long bed) that I am converting for my 66 GMC.
So far I have found the following;
Bed mounting location dimensional differences between both frame types noted.
Frame horn and core support detailed locational measurements and have started a how to photo layout.
I also have the rear cab mount frame tower information.
Basically, I am building a step by step instructional of how to convert the 68-72 frame to use on a 63-66 cab in office format and will post it here when I am done.
I also have the frame horn power steering graft to finish. I used my 63 SWB truck for an example as I put a power steering gear box on the 63. I didn’t use the adaptor on this truck.
I have vacation starting after Monday so I should have time to do some of this.

[66-PMD-GMC]

Update on my updates.
I have made extensive measurements and found the following differences in the 63-66 frames compared to the 67-72 frames. Long bed.
The rear section of the frame under the bed is the same except for four bolts that hold down the bed. The front hold down bolts closest to the cab are different by a 1/4 of an inch and a set of bolts near the tail gate are missing all together.
The rear cab mounts are not only lower but they are also farther out on the earlier cab. (63-66 compared to the 67-72)
The core support/radiator cross member and core support mounting brackets both need to be changed out. Height and location differances are present between the frames on those core support mounts.
Donors from the old frame can be used.
The end of the frame horns where the bumper bolts to the frame by 4 bolts are also something that needs to be grafted in. About 3 inches looks good.
I shortened mine a bit to tuck in the bumper in for a smoother look.
I have most of this on a cad drawing and I am including the GMC (leaf rear sprung) and the Chevy setup (coil sprung) 63-66/67-72 conversion.
My frame is out to be blasted and when it comes back I will get the after photos to post.

[66-PMD-GMC]

This post is to show the front part of the converted 71 frame so it will take take the 63-66 core support and radiator support brace.
The red arrows show the two center lines of the two different year core support frame supports.
3/4 inch is the difference in location of the center lines along the frame and it should be clear to anyone that the supports need to be changed out.
You can see the two perches together in the second photo.
The distance between the yellow arrows is 2 inches and between the orange arrows is also 2 inches.
The yellow arrow on the right in the photo shows the center line of the rivet hole that locates and holds the original 71 cross member.
(I left the 71 brace in as it isn't in the way of what I am doing and it is where the proportioning valve mounts in my project.)
The total dimention is 4 3/4 inches total from the center line of the factory hole for the factory 71 cross member to the centerline of the core support frame perches need to use the 66 stuff.
The black arrow shows a factory hole that is directly on center with the core support holes. If a person were to establish this hole on each frame horn he can find the holes needed for the 66 radiator support brace and also have something to measure from for welding on the ends of the frame horn so the correct bumper can be used.

[jmcdaniel]

That's awesome. i needed that information for sure. i've got a front end that i was able to cut off a junk 63 a few months ago and this information is just what i needed. thanks. if you notice anything else that needs to be changed please post it. i was able to get 63 cab supports that will help put everything together.

[66-PMD-GMC]

I forgot to mention heights.
The top of the 63-66 core support perches are mounted 1/2 inch above the frame.
I clamped a metal level on to the perches and used a 1/2 inch shim between the level and the frame and C-clamped the perches to the frame.
Making sure the top core support perch holes of were on center line and everything is very tight, I used the perch itself as a template to drill the 3 mounting holes on the side of the perches through the frame.
Grade 8 shoulder bolts and self locking nuts were used throughout.
I also have the dimensions for the cab mounts.
They are mounted and there is a stripped mock up cab on the frame right now.
When the cab is off I will post photos of that as well.
I was told that some of the holes line up on the rear cab perches. None did on my 3/4 ton but I am told the 1/2 ton is different.
It doesn't matter. What I have will work either way since all of the measurements are taken from the top and sides of the frame.
The frame is finished except for the profile of the nose of the frame horns where the bumper mounts.

[SCOTI]

Originally Posted by 66-PMD-GMC

I forgot to mention heights.
The top of the 63-66 core support perches are mounted 1/2 inch above the frame.
I clamped a metal level on to the perches and used a 1/2 inch shim between the level and the frame and C-clamped the perches to the frame.
Making sure the top core support perch holes of were on center line and everything is very tight, I used the perch itself as a template to drill the 3 mounting holes on the side of the perches through the frame.
Grade 8 shoulder bolts and self locking nuts were used throughout.
I also have the dimensions for the cab mounts.
They are mounted and there is a stripped mock up cab on the frame right now.
When the cab is off I will post photos of that as well.
I was told that some of the holes line up on the rear cab perches. None did on my 3/4 ton but I am told the 1/2 ton is different.
It doesn't matter. What I have will work either way since all of the measurements are taken from the top and sides of the frame.
The frame is finished except for the profile of the nose of the frame horns where the bumper mounts.

Looking forward to the progress pics (hint, hint....).

[66-PMD-GMC]

Originally Posted by SCOTI

Looking forward to the progress pics (hint, hint....).

Here is the rear cab mount.
The height is set at 1 inch above the top of the frame. The frame is straight where the cab perches bolt to the frame.
Again, I used the perches as templates, drilled the holes with 2 c-clamps holding it to the frame.
The dimensions will be posted when I get the cab off the frame, along with the photos.
I was a lot easier with another frame here to take dimensions.

[66-PMD-GMC]

This is the 63 cab on the frame. The 66 is the truck that will call that frame home unless I get all crazy and change my mind.
Of course, that never happens... I am so full of it... lol

[66-PMD-GMC]

*IMPORTANT UPDATE!*

Wholly freaking carp!

Measure 3 times cut once. That has been my motto for decades.
I found out this morning that it works if you are measuring the right thing.
You will notice in the photos that I put a 24" level on the top of one of the 63 frames I used for dimensions when converting the 71 frame for my 66 work truck.
The reason.....
I started the final step of doing the ends of the frame horn so I can bolt a bumper on when I am done.
Well, when measuring I found that the 71 frame horn seemed lower than the 63.
Measuring this I found that the 71 frame horn sits exactly 1" lower than the 63-66 frames.
This means that the core support perches I just mounted are too low and possibly the radiator brace.
From the bottom of the level to the top of the frame on the 63-66 frame is 3 3/16ths" The same measurement on the 71 is 4 3/16ths!
I put a clip back on with fenders this time and my core support perches are an inch too low.
This is with my 3/4 ton frame. I haven't checked a 1/2 ton but..........
crap!

[66-PMD-GMC]

Solution to frame horn height problem.
When I took the 67-72 core support brackets off the frame it left 4 holes on the frame.
I used the forward lower hole to locate the bottom hole on the 63-66 3 hole core support brackets. This located the center of the brackets in the right place and the height of the bracket is 1" above the top of the frame horn. I used 2 bushings I had laying around that put 1/2 inch between the bottom of the core support and the top of the bracket putting the core support right where I needed it.
I will use spacers between the radiator support and the two U shaped brackets to raise them when I install the radiator.
When I graft in the frame horns to support the bumper I will C clamp them on first, mount the bumper and set the height. Mark everything after that and them weld them in.
This was not the easy conversion I thought it was going to be. I will have photos soon of it completed.
The photo of the core support bracket is off the internet since I threw away the old brackets. They get the point across I hope.

[chad64chevy]

when i started mine i didnt even notice the 1 in. differents, i'm using new 60-66 cab bushings and then radiator support bushings from a 60's chevelle that are thick! i was thinking of on how most grille supports are cracked or bent from being hit on the frame rail, the thick bushings would fix that!! i havent tried to put a radiator in either so thanks for letting me know about that too!! i planned on lowering my front bumper anyways and filling in that saddle, so i think i'll just line it up and call it good!!

[66-PMD-GMC]

I was just looking into deleting the bumper.
Not sure how that would look.

[Raceaprilia]

I am doing the same frame swap thing with exception I do not have 64-66 frame to take measurements from and need help. Just to clearify before any cutting; front cab mount is in exact same position on 64-66 and 68-72 frame (height of the mounting holes for cab is 3,38" below frame rails, mounts have 1.30" opening to bolt cab on and measure 41,25" - 41.50" apart across frame). Rear cab mount is lifted 1,06" above frame rails and is 41,63" behind front mount (measuring center of both 1.30" mounting holes). Holes are 42,20" apart across frame rails. I got this info from different treads and drawings over here on forum but just want to make sure to do it right the first time. Could somebody with bare frame out of 64-66 beside him take measurements and confirm above measurements? Thanks! If something does not match please write down right dimension.