The Stovebolt Site Forums The Parking Lot Big Bolts 1954 450 GMC differences between 1956 450 GMC

What are the differences in chassis between the 54 and 56 450 GMC's. I know the body is very different.

Both have 302's

Wheels and tires
brakes
Rear's (both 2 speed)
Tranny's
Frames
hoist and flatbed
Driveshaft
springs

The 56 had an automatic which was switched to a 4 speed. Wasn't there some frame changes that needed to be done to support the different transmissions.

The 56 might be more of a parts truck for the 54 in time.

I hope I am not asking to much.

What do you have in mind, that may help those that know point out the differences that matter or effect your plans.

Aren't 54 and 56 completely different body styles?

Grigg

The 450 is like larger trucks that were speced for the purpose of the truck. Wheels could be stud piloted or open center Dayton. Brakes could be hydraulic, air over hydraulic or straight air. The original transmission would have been a 5 speed with several options available. The rear would probably be the same except the 54 a 6 volt electric and the 56 a 12 volt electric. The 5 speed would not have a cross member for the transmission. I don't know what an auto had. I 450 should have a double disc clutch. They probably used a single disc clutch to mate to the 4 speed. The frame would depend on the wheelbase. Both would have a 34" wide frame. The hoist and body would be whatever someone installed. The driveshaft would probably be different length and who knows what they used to put in a 4 speed. The springs would probably be the same.

Let's see some pictures Bruce. I love the 400 series, & larger '47-'55.1 GMC trucks. I like how the wiper motors were moved above the windshield on the '54/'55 450, & larger Jimmies.

Hey, Bruce,

Drive one to Macungie, if possible.

You probably won't want to keep both 302s. I could probably get the '56 to work fine in my 54/55 350 COE.

Good luck with this project.

I just have the 54 at the present time and looking for parts like wheels, brake drums and tires and hoist. Whatever else crops up in the future. But just mechanical for the time being. Both have electric rears.

The 56 is ready to be junked far away in MN. It has good wheels and tires, hoist and running 302. My 54 has bad brakes tires and no hoist. Wheels are motor wheels. Engine does not run yet.

I do not know how to send pictures. Just dreaming as usual. This is addictive. Grigg has seen a picture and probably knows more about my 54 than I do just looking at a picture.

Does the transmission usually just hang from the bell housing. And an Automatic has a crossmember to support it. I do not have it close to me but it does have a 5 speed.

Not to interested in the body at this time. but who knows in the future. I would rather find another 54.

Yes wipers are really neat. Sun visor would even be better.

Tim, you can't have a 302 yet. We are going to have a pull one day with your 350 COE. (just kidding). Anyways your engine is upside down when I look at the manual.

thanks for the feedback everyone.

Bruce, open up the glove box, & on the back of the glove box lid should be a "GMC Parts Identification" tag, with all your trucks vital statistics on it, ie. eng. type, trans. type, wheels, brakes etc. Have you noticed it also has the small round park lights(not square, with grille surround encompassing them, like on 350 series , & smaller '54/'55 trucks), & larger fenders.

Correct, it has the older style small round lights.

Spanky,

Yes I noticed the small round lights immediately. Like the wipers. Then the horn button is different. Going out of town for a week so last message from me for a while.

bruce