47-55.1 100 Series vs 300 Series truck questions.

[Richard8971]

Hey all...

I have a 1948 GMC 300 14' flatbed truck. I have done some research and the general thoughts on putting them on newer frames is this.

If it's a 100 Series you can use an S-10 frame.

If it's a 300 Series you can use the C10 frames because of the wider fenders and longer nose.

I don't have a problem per se' in leaving the truck original but I'm sure that running gear needs a ton of work and it would be so much easier to start off with newer running gear that is in decent shape.

My question is, if I use a C10 frame to make a 1/2 ton out of it, has anyone else done this? Do you know of any finished trucks with pics? How about the rear fenders... do you have to widen them as well? The wheelbase between the 100 series trucks and the C10 frames are within a few inches so all of that can be dealt with.

Thanks for any help you can give!

D

[weim55]

What I wonder about is the wheel opening diameter on those front fenders. They are HUGE! It would take some serious tires to fill those up and look proportional. I've seen a truck or two like yours put on a 4x4 frame with big 36s or so and they look pretty good!

Steve weim55 Colorado

[mr48chev]

Outside of trimming the inner fenders a bit I don't think you will have much of a problem. The frame widths are real close on that truck and the 73/87 C 10 or other GM trucks of those years.
I'd cut the rivets on the cab mount outriggers on the old frame and move them to the new frame the exact same distance from the axle center line.

This is Chevy but if you scroll down to page 59 you will find the body and tread widths that should match the 300 GMC when you look at the 4000 series Chevy.

Fenders should be 78-7/8 outside to outside compared to 72 and 5/8 on the 3000 series or 1/2, 3/4 and 1 ton. The bigger and taller openings prevent some of the tire rub issues that the 1/2 tons have with bigger tires but do need a bigger tire to look right.

A lot of GMC 1/2 tons had long beds on them so a long box wouldn't be out of place if you ended up with a later longbed frame. Lots of ways to go with that one.

[mongocanfly]

If your making a pickup out of it another visual part is the rear fender openings won't be even close to the front openings...I've given much thought to using one of these big truck cabs but like said..it takes a big tire to make it look right....

[dsraven]

are the actual cabs not the same as the smaller trucks and the change is the size of the hood and fenders on the larger trucks?
if you are ok with the longer front end when installed and made into a 1/2 ton, why not simply trim out the wheel openings to match the 1/2 tone size wheels? you could even do that while it is sitting on the original frame-as is- and slip a smaller tire into the opening to see if you like it before doing all the work.
you could use the cab from the larger truck and fenders/hood etc from a smaller truck and then widen the fenders to fit over the wider stance
either way it is gonna be some work but it might be fun work, like a hobby is supposed to be.
buy some coveralls, safety glasses, a beanie or a cap, some nitrile gloves and hand cleaner, then set some time aside for the project and most importantly, post pics. lol.
seriously, take lots of pics of the way things go together as you take them apart. keep associated parts together and install the bolts/nuts/fasteners back in their locations on the parts so you know what went where.

[Richard8971]

Ok... thank you everyone for the input. I had not taken into consideration the wheel well opening size.

This pretty much answers my question.

D

[_Ogre]

Originally Posted by Richard8971

I don't have a problem per se' in leaving the truck original but I'm sure that running gear needs a ton of work and it would be so much easier to start off with newer running gear that is in decent shape.

while you might be a few years newer, the last c10 was 80s and will probably need to be totally rebuilt to be usable