79 GMC Street Coupe - Stock Drivetrain

[KCJim]

Is there a way to find out the exact motor, transmission, rear end, and chassis configuration for a 1979 GMC pickup at the time it was built at the factory. Am I overthinking it? I have the RPO codes from the glove box, but they stop short of determining things like 2 or 4 bolt, 350 or 400 transmission, rear end and braking, and stuff like that. I know what I have, and it came to me by way of a 2000 mile trek from WA, so I know it worked. past tense. I'm disassembling now and trying to decide how far to go and with what.
Thanks, in advance
KCJim

 

[legopnuematic]

Being an F44 (big 10/heavy half) equipped truck it would have JB5 brakes (2.75" wide rear shoes).

A 350 engine should have gotten a TH350 transmission, the rear would be a 12 bolt, as I do not see anything on the spid sheet designating a ratio, it would likely be 3.07.

My 79 Big 10's 350 is a 2 bolt main block, id expect most 1/2 tons to be 2 bolt blocks. Just a guess there.

 

[Ricko1966]

Tried to add a link to rpo codes here. The link didn't work and there wasn't much on the sticker that needed looking up any way. Sorry.

 

[Keith Seymore]

There might be some additional detail here:

Link==>https://www.gm.com/content/dam/comp...its/chevrolet-trucks/1979-Chevrolet-Truck.pdf

 

[Keith Seymore]

Looks like it was built in Fremont ("Z" in the VIN).

Model decodes as

T = GMC nameplate
C = 2wd
1 = 10 series 1/2 ton
07 = short wheel base
03 = 2 door regular cab

 

[xm20k]

350 2 bolt
tH350 with 9" output/tail housing
12 bolt rear
bigger brakes front and rear

Not sure on gears but mine was 3.45 if I remember correctly.
Also bought from Washington

 

[Ricko1966]

350 2 bolt
tH350 with 9" output/tail housing
12 bolt rear
bigger brakes front and rear

Not sure on gears but mine was 3.45 if I remember correctly.
Also bought from Washington

You pretty confident on that gear ratio? Not being pissy. Just acquiring info. Thinking I'm go down from god knows how many trucks I have(I think 8)to one. And I'm thinking I'm going to model it after a 1979 ish Big 10. I think it will cover the most bases for doing truck stuff.
Big Brakes,stiffer springs,350 qjet,long tail th350 is the plan,but was thinking 3.08 gears.

 

[xm20k]

You pretty confident on that gear ratio? Not being pissy. Just acquiring info. Thinking I'm go down from god knows how many trucks I have(I think 8)to one. And I'm thinking I'm going to model it after a 1979 ish Big 10. I think it will cover the most bases for doing truck stuff.

Pretty sure it was. At one point I was going to rebuild and regear it before I just said screw it and swapped the 9" in and that's the number that comes to mind.

 

[legopnuematic]

1979 Vehicle information kit

You must be registered for see images attach

 

[xm20k]

Dug out the sticker nothing about rearend. But I'm almost positive it had 3:45 stamped in the ring gear, may have been changed.

You must be registered for see images attach

 

[KCJim]

Being an F44 (big 10/heavy half) equipped truck it would have JB5 brakes (2.75" wide rear shoes).

A 350 engine should have gotten a TH350 transmission, the rear would be a 12 bolt, as I do not see anything on the spid sheet designating a ratio, it would likely be 3.07.

My 79 Big 10's 350 is a 2 bolt main block, id expect most 1/2 tons to be 2 bolt blocks. Just a guess there.

Thank you. I confirmed all but the brake size (on dollies currently) on the F44. Ironically, I found a Heavy Half sticker on the inside of the right fender. I think it's starting to communicate with me. LOL.

Now we enter the unknown I was trying to solve, or was overthinking, simply for consistency's sake. As for the LS9 RPO, the 350 engine part is confirmed from the RPO, but not all of the engine info like 2 or 4 bolt is given ( I was wondering if the 4 in the RPO description sheet I provided might give a clue to the trained eye). Same with MX1 for Transmission, and some of what I read indicated the engine 2 or 4 bolt designation accompanying an F44 often received the 400 as a more HD 3 speed in those configurations. the 400 replacing the Might explain the Yellow arrow on the transmission side drive shaft, might be a giveaway. Figuring out what other people did and why is hard.

I'll drop the oil pan tomorrow to make sure of 2/4 bolt. It came from Hi-Tech Engines in Spokane, and I spoke with A person who used to work in that company. Great guy, Bill I believe.

 

[KCJim]

Tried to add a link to rpo codes here. The link didn't work and there wasn't much on the sticker that needed looking up any way. Sorry.

Thanks I have several links already, and I have RPO Code fatigue.

 

[Keith Seymore]

As for the LS9 RPO, the 350 engine part is confirmed from the RPO, but not all of the engine info like 2 or 4 bolt is given ( I was wondering if the 4 in the RPO description sheet I provided might give a clue to the trained eye).

No. The "4" is where they started to say "4 bbl carb" and just ran out of space.

K

 

[KCJim]

There might be some additional detail here:

Link==>https://www.gm.com/content/dam/comp...its/chevrolet-trucks/1979-Chevrolet-Truck.pdf

Thanks, got em. I think I plucked it from a prior thread here. I've scavenged the resources and info talked about here as far as I can. I'm trying not to ask questions that have already been answered.

 

[KCJim]

Looks like it was built in Fremont ("Z" in the VIN).

Model decodes as

T = GMC nameplate
C = 2wd
1 = 10 series 1/2 ton
07 = short wheel base
03 = 2 door regular cab

Copy, Thanks I got that from the Manuals and research here on GMSB. Much appreciated.