Trans question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**slomotion** · 09-27-2006, 05:22 PM

I hope I can describe this without writeing a book! I have a '68 C20 factory dually with a 9'6" flat bed rack body. It has a 292 and a rock-crushing 4 spd trans. I'm hauling the trans and engine out in prep for body paint and useing the opportunity to clean up and detail the engine. (Paint, new gaskets, a few goodys etc.)

The trans is a 117 mm unit and is almost as big as a small block eng. What I'd like to do is put an AOD in it. The engine bellhousing is mounted to a riveted cross-member which is the rear mount and the trans is bolted to the bellhousing with no support under it. I know a small V8 bell housing will bolt up to the 292, I'd need a flex-plate, torque converter, etc, and I suspect I'd have to modify the drive shaft. Would I have to create another cross member to support the auto trans?

Has anyone done this? I don't mind the shifting, but for the size of this monster, I essentially only have a three spd because 1st is low enough to climb trees, but is used up in 25 yards, so 99% of the time I leave in 2nd. This is not a race truck, or a work truck just a fun get-around-town type of ride.

Thanks for your input!

JAKES 68GMC · 09-27-2006, 05:28 PM

Nice looking 1-ton there. Can't help with the trans swap, though.

70rs/ss · 09-27-2006, 06:14 PM

Yeah, all the stuff from the 4-speed goes, including the crossmember. I'd look for a parts truck with an auto or maybe a wrecking yard, because it is kinda troublesome to try and put it together piece by piece. The driveshaft'll need replaced or remade with a slide yolk.

Longhorn Man · 09-27-2006, 10:13 PM

Also, being a one ton, the frame is taller than a 3/4 ton or 1/2 ton (longhorns not included, they all used one ton frames) The automatic tranny crossmember is the same for all chassis, they simply added spacers to take up the extra space.
If interested, I actually have a set for sale, PM me if interested
http://67-72chevytrucks.com/vboard/c...ct=250&cat=500 (the one on that thread ended up passing... I still have them here for sale, and can send you photos to e-mail if interested)

TP from Cntl PA · 09-27-2006, 10:19 PM

An NV4500 5spd would be nice in that truck.............Last forever too.

**slomotion** · 09-28-2006, 11:23 AM

TP, I must have been living under a rock. I'm not familiar with a NV4500. What's it out of? Is the 5th gear an OD? Does it replace my current trans without mods? I'm talking with Longhorn about some brackets that I suspect I'll need whether I go 5 spd or AOD.

Thanks

70rs/ss · 09-28-2006, 12:45 PM

NV4500 is the bullet proof version of the an overdrive, but it is standard. 1st to 2nd is way better than the 4-speed you have now. They came in newer 3/4 or 1 tons. You will still need to swap out the crossmember. WARNING though, these things run in the $1k and up neighborhood, but as stated above they will last forever.

**slomotion** · 09-28-2006, 05:47 PM

Thanks for the info 70rs/ss. I guess that means a th...th..thousand huh?
I'll look around here and see what I can scrounge up.

Thanks again

TP from Cntl PA · 09-28-2006, 09:45 PM

I don't know much about Autos(Don't like them myself), but do you think you could swap an AOD in for less than an NV?

**slomotion** · 09-29-2006, 08:15 AM

Hi TP, Not sure about the costs involved in going either way....I guess this is where the homework comes in. The good thing is our season is virtually over, (Maine) so I've got the winter to figure it out and build something.
Thanx for your input!

09-27-2006, 05:22 PM	#1
slomotion Old Duffer Join Date: Mar 2003 Location: Maine Posts: 1,822	Trans question I hope I can describe this without writeing a book! I have a '68 C20 factory dually with a 9'6" flat bed rack body. It has a 292 and a rock-crushing 4 spd trans. I'm hauling the trans and engine out in prep for body paint and useing the opportunity to clean up and detail the engine. (Paint, new gaskets, a few goodys etc.) The trans is a 117 mm unit and is almost as big as a small block eng. What I'd like to do is put an AOD in it. The engine bellhousing is mounted to a riveted cross-member which is the rear mount and the trans is bolted to the bellhousing with no support under it. I know a small V8 bell housing will bolt up to the 292, I'd need a flex-plate, torque converter, etc, and I suspect I'd have to modify the drive shaft. Would I have to create another cross member to support the auto trans? Has anyone done this? I don't mind the shifting, but for the size of this monster, I essentially only have a three spd because 1st is low enough to climb trees, but is used up in 25 yards, so 99% of the time I leave in 2nd. This is not a race truck, or a work truck just a fun get-around-town type of ride. Thanks for your input! Attached Images __________________ '68 Short C20 Flatbed Dually w/ 292 4bbl, Langdon cast headers, and WC T5 trans. '81 G10 Shorty Van "Good judgement comes from experience, and a lot of that comes from bad judgement." Will Rogers "Under promise, then over achieve."

09-27-2006, 05:28 PM	#2
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,211	Re: Trans question Nice looking 1-ton there. Can't help with the trans swap, though.

09-27-2006, 06:14 PM	#3
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,270	Re: Trans question Yeah, all the stuff from the 4-speed goes, including the crossmember. I'd look for a parts truck with an auto or maybe a wrecking yard, because it is kinda troublesome to try and put it together piece by piece. The driveshaft'll need replaced or remade with a slide yolk.

09-27-2006, 10:13 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Trans question Also, being a one ton, the frame is taller than a 3/4 ton or 1/2 ton (longhorns not included, they all used one ton frames) The automatic tranny crossmember is the same for all chassis, they simply added spacers to take up the extra space. If interested, I actually have a set for sale, PM me if interested http://67-72chevytrucks.com/vboard/c...ct=250&cat=500 (the one on that thread ended up passing... I still have them here for sale, and can send you photos to e-mail if interested)

09-27-2006, 10:19 PM	#5
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Re: Trans question An NV4500 5spd would be nice in that truck.............Last forever too. __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

09-28-2006, 11:23 AM	#6
slomotion Old Duffer Join Date: Mar 2003 Location: Maine Posts: 1,822	Re: Trans question TP, I must have been living under a rock. I'm not familiar with a NV4500. What's it out of? Is the 5th gear an OD? Does it replace my current trans without mods? I'm talking with Longhorn about some brackets that I suspect I'll need whether I go 5 spd or AOD. Thanks __________________ '68 Short C20 Flatbed Dually w/ 292 4bbl, Langdon cast headers, and WC T5 trans. '81 G10 Shorty Van "Good judgement comes from experience, and a lot of that comes from bad judgement." Will Rogers "Under promise, then over achieve."

09-28-2006, 12:45 PM	#7
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,270	Re: Trans question NV4500 is the bullet proof version of the an overdrive, but it is standard. 1st to 2nd is way better than the 4-speed you have now. They came in newer 3/4 or 1 tons. You will still need to swap out the crossmember. WARNING though, these things run in the $1k and up neighborhood, but as stated above they will last forever.

09-28-2006, 05:47 PM	#8
slomotion Old Duffer Join Date: Mar 2003 Location: Maine Posts: 1,822	Re: Trans question Thanks for the info 70rs/ss. I guess that means a th...th..thousand huh? I'll look around here and see what I can scrounge up. Thanks again __________________ '68 Short C20 Flatbed Dually w/ 292 4bbl, Langdon cast headers, and WC T5 trans. '81 G10 Shorty Van "Good judgement comes from experience, and a lot of that comes from bad judgement." Will Rogers "Under promise, then over achieve."

09-28-2006, 09:45 PM	#9
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Re: Trans question I don't know much about Autos(Don't like them myself), but do you think you could swap an AOD in for less than an NV? __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

09-29-2006, 08:15 AM	#10
slomotion Old Duffer Join Date: Mar 2003 Location: Maine Posts: 1,822	Re: Trans question Hi TP, Not sure about the costs involved in going either way....I guess this is where the homework comes in. The good thing is our season is virtually over, (Maine) so I've got the winter to figure it out and build something. Thanx for your input! __________________ '68 Short C20 Flatbed Dually w/ 292 4bbl, Langdon cast headers, and WC T5 trans. '81 G10 Shorty Van "Good judgement comes from experience, and a lot of that comes from bad judgement." Will Rogers "Under promise, then over achieve."

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