question. is a 91 c-30 still a square body

[travlinman]

As it states is a 91 chevy c-30 crew cab dually still considered a square body?
I have a 78 crew dually that has a rotted cab. Rockers- windshield frame and a pillars are gone. I found a 91 crew/dually with a rod knock for cheap. So I got to thinking y not just swap motors (both 454) and front clips (i like the older front ends) and upgrade to a newer cab with power windows and locks and a overdrive trans. Than I could part out what I have left and get some money back.
Thoughts and suggestions please.

[Cabnchassis]

My 91 is a square but it's an R3500. All square burbs and crew cab trucks had the R model designation until they ended in 91 IIRC. All C/K model trucks from 88 forward are GMT 400 as far as I know. the logic works out too my 91 R model is a square but my 92 is a gmt 400 and is a K model. I could be wrong but I doubt it.

['68 Newtricks]

I would say so. Just make sure and take some frame measurements before you pull the purchasing trigger. Then swap away!

[travlinman]

Thanks guys wasn't sure where the 1 ton -30 ' s cab stopped. I've seen the front clip I'm buyin on older cabs so I'm thinking it should work the other way.

[old Rusty C10]

squarebody is the unofficial description of the genre so as long as parts will interchange from the body to a 73-87 truck or 81=87 truck it is still a square body

[Bigstevex4]

4 doors not standard cabs got a 90 square body jimmy

[noco-k5]

I also have a 1990 Jimmy. The board should have a square body forum since the years are different depending on the model. This section is much more active than the others.

[bluex]

If it's a crew cab it's still a square body an it's an R30. The regular an extended cabs changed in 88 along with the half tons but the crew cabs stayed the same body style as 73-87 until 91 like the suburban an k5 did.

[mattybilt79]

If I'm reading this correctly you want to swap your 78 motor and front clip over to a 91 truck. By the time you pull your motor out and pull the bad motor out of the 91,swap all the accessories and TBI parts, exhaust and do pm stuff like timing chain and rear main since the motor is out. Then deal with the 20 plus year old wiring harness which will have brittle wires and at least a few broken connectors no matter how easy you are when disconnecting them. It could be done but you would have two non running trucks and a can of worms of other issues to deal with. The 91 should have a 4l80e like you stated overdrive which is a plus but from my research and personal experiences a total pain in the ass when they go bad. It would be a big job just to upgrade to power windows and locks. I would either rebuild the motor in the 91 or find a year compatible motor to put in it and then add your front clip when its running and driving or keep looking for a compatible pre 80 truck with the accessories you want that needs a motor to swap out your 78.

[travlinman]

Mattybilt u are correct that if i buy this 91 I will be swapping motors and front clip from my 78.
Motors are easy taking 2 out and 1 in. mainly swapping the front drive system and upper intake and a few gaskets. Front clip should be a easy direct swap only figuring out the headlights. Again 2 off and 1 back on. Everything coming out or off will be sold off at some point. It's easier than trying to find a complete cab to swap for my 78 or redoing the underdash and door wiring with power stuff.this way I know everything works (wiring-windows a/c )before I pull it apart. I know the headache of the 4l60e trans I just pulled out of my 97 to rebuild last month.
I'm in no hurry it's a long term project that will be bagged on 22 semi wheels when it's done. I work /drive for a trucking company hauling and delivering gas - avgas and jet fuel so I've got a free set of semi wheels airbags lines etc..and our lead diesel mechanic helping out.
Thanks everyone for the help so far it should be fun tackling this.

[mattybilt79]

If its a long term project then i say give it a shot. I just did the opposite and stripped a TBI 454 down and put a carb on it for my 85 dually. Amazing what a couple years of engineering did to make the same motor run with a computer.

[travlinman]

Ok another question. Since the later crew cabs are kinda lost what should I be looking for when ordering new carpet-interior? Refer back to pre 87 or look for something around 91 like a suburban?

[nekkidhillbilly]

Originally Posted by mattybilt79

If I'm reading this correctly you want to swap your 78 motor and front clip over to a 91 truck. By the time you pull your motor out and pull the bad motor out of the 91,swap all the accessories and TBI parts, exhaust and do pm stuff like timing chain and rear main since the motor is out. Then deal with the 20 plus year old wiring harness which will have brittle wires and at least a few broken connectors no matter how easy you are when disconnecting them. It could be done but you would have two non running trucks and a can of worms of other issues to deal with. The 91 should have a 4l80e like you stated overdrive which is a plus but from my research and personal experiences a total pain in the ass when they go bad. It would be a big job just to upgrade to power windows and locks. I would either rebuild the motor in the 91 or find a year compatible motor to put in it and then add your front clip when its running and driving or keep looking for a compatible pre 80 truck with the accessories you want that needs a motor to swap out your 78.

cant he just put the tbi intake and accessories on the old block?

[bluex]

Originally Posted by travlinman

Ok another question. Since the later crew cabs are kinda lost what should I be looking for when ordering new carpet-interior? Refer back to pre 87 or look for something around 91 like a suburban?

I look for an 87 usually just so I make sure I get the right thing.