The Stovebolt Site Forums The Shop Area General Truck Talk Chevy/GMC Differences

Hi, new to the board and to these old trucks in general. I just picked up a 49 GMC PU. What are some of the differences between the Chevy and GMC? Just cosmetics or any chassis items, etc. Not sure exactly what I want to do yet, but definitly a mild rod anyway. Thanks

Welcome to the board

The difference GMC and Chevy......GMC has a long truck motor
Chevy has a short car motor

Beware of "Long motor envy"

You own a good basis for a Hot Rod

Jimmy's just go faster longer!!!!

GMC & Chevrolet Built their own trucks back in the days before about 1970. They are not the same in many ways, Engines was a big difference, but on some of the older ones I have heard tell that even the entire front clip is not the same.

GMC built trucks to work, and sold most truck day in those days to folks who worked trucks. Chevy on the other hand built trucks for the family, using a lot of non truck items like car engines.

But if you planning on hot rodding, I hear tell that the GMC inline engine is a better place to start than a Chevy, but if your tossing the engine in favor of a small block V8, well even a Dodge makes a good project. I would have said ford but you all know what happen when you type the four letter f-word.

Well, most GMC's are fugly and Chevy's purdy.

The cosmetic differences you know about.

The motor is significantly different but bolts to the same bellhousing. Its also bigger than the same year Chevy. The has higher nickel content in the block, which makes it better suited for hot-rodding. Full pressure oil earlier. And I think there are some crank differences, but don't recall any details.

The radiator is mounted further forward to make room for that long motor.

The front crossmember is setup to mount that long motor, and drops down lower where the radiator frame attaches.

There may be others, but those are the ones I think of.

Thanks for the replies. I do not plan to use the original motor, more than likely going to a small block. Is the wheelbase any different? Are the fenders and hood the same other than the parking lights in them? Will the front brakes swap kits from a chevy work on these the same? I have really nothing here to compare to and this is my first real involvemnet in a truck, been doing musclecars for a long time so this is all new. Thanks

Hood is different. Fenders might be the same, not sure, depends on the grill I guess. Rears are probably the same. Check out the pictures in the gallery for comparison. I know, I wish they were bigger too.

The hood, fenders and grill are cosmetic differences...

The fenders are different because the GMC has holes for the parking lights, where on a Chevy the parking lights are in the grill. On a '54 or '55 1st where the parking lights are in the grill mustache its not an issue, but for the earlier AD trucks this is a significant difference.

The GMC grill design stands taller and therefore the hood is different to allow room for the grill surround. The holes for emblems and badging would differ too.

I would really prefer to make it into a Chevy. Is that taboo in the truck world?...lol. Thanks for all the help.

Not in the "Truck World" just on these pages! There are some die-hard GMC fans here. There is also some good sites out there that deal with GMC's. I have seen some very nice restored and rodded GMC's too. Converting a GMC over to a Chevrolet is easy, get a complete front end from a truck (at least a chevy hood and catch mechanism and a chevy grille), change the front cross member and you now have a disguised GMC. Wheel bases are the same, in fact there is very little difference outside of the engine and some beefed up suspension.

Change a GMC into a Chevy???

Make sure to box up all of the GMC parts that you take off of your truck and ship them to me. I will be happy to dispose of them for you.

There are GMC guys here.....many of the Chevy guy have never seen a GMC that's really true with prewar trucks

As for GMC guys vs Chevy......... Foooooooooey!

People here love trucks and you do as you please It's,after all, yours

I will tell you that if you want a Chevy you should buy one You'll
be time and money ahead

AD's in 'Hot Rod-able' shape are pretty easy to find

There's room here for every level of interest

I've owned em both--jimmi motors were a little stouter--it seemed to me--some of it could have been the tranny==sm420 on my jimmi--don't know. Sheetmetal and other runnin gear pretty much the same. Don't know anything about nickel content of blocks or cadmium bolts. Truth is a lotta of this old iron is getten hard to find--particularly AD and earlier--buy what you can find and enjoy it. GMC or Chevy makes little difference--gud stuff is wore out anyway.

Be aware if you cross the border to the north this all changes again!

Canadian GMC's have Chevrolet drivetrains.

Before you take a cookie cutter and install a small block Chevy like 90% of the people that re-power an old truck or car take a look at this picture. It might inspire you to dare to be different.

nice one Cletis

That is pretty cool I must say. We are a long way off still, I dont even have it im my driveway yet, have to go pick it up this weekend if the weather looks OK here.

Cletis, that is not even a truck!

I never said it was a truck. I posted it to stress the point that everybody and their mother repowers old trucks and cars with small block Chevys. I was at a local show Sunday and I swear 90% were powered by, you guessed it. Does anyone have any imagination?

Hmmmmm--

Guess car motors aren't just for Chebbies anymore. GMC bus motor in a car--hope Profit don't get upset.

Buzzin
I'm putting a dry sumped 12port FI 302 motor in a '40 Ford comp coupe Dry Lakes racer done by Sam(NOT Geo.!!!) Barris in the late forties

I love seein Chevy coupes with GMC Motors....many real sleepers were built in the Fifties

The important thing is 'Run hard or GO HOME'

I won a lotta money from the AD guys here Street Racing the 228!!!!

My son's '46 1/2 ton will likely end up with a 383...and we're NOT talkin' stroker Chevy engines, either!!!

Have u guys sen the ebay ad of the chevy with the diesel engine in it. A bunch of people have bid on it.

It's fine and dandy talking about keeping the straight 6 but if you need a reliable 350ft/lbs to tow a trailer at highway speeds that kind of power can get expensive when you're sticking with your inline 6 (Chev or Gmc)and electing to upgrade it instead. If there were stroker kits and the like floating about for the 6's then I am sure a lot more people would prefer to fiddle with what the truck came with.

Torque??

302 Has lottsa.....I've got a dyno stub 1 3/4 and TWISTED!!

This year the boy's went 294 @ B'ville

It's hard to explain how really powerful these engines can be to those of you that have never see heard or driven anything powered by a JIMMY

My 12port will make a nice strong 400 hp as a mild street tune engine

Yup. Even a stock 248 has a ton of torque. I'd love to find a 302 for the '51 350, though.

The panel is getting a later model 250 equipped with fuel injection. I like the idea of having 7 main bearings, and since it will be a regular driver, the cheaper parts are also a bonus. It's 248 will stick around, I'll find something to do with it.

Well, the 302 is around 260 standard, and there doesn't seem to be a huge amount of interchangeable parts out there for it. I wondered about getting a bigger GMC inline 6 instead but the 400" plus engines don't exactly seem to be thick on the ground. What would you suggest to up the 302 to closer to 400ft\lbs while keeping the torque down low in the power band and maintaining reliability?

There's been two 302's (complete engines) come up on ebay recently.