The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 1951 GMC Floor High Hump

mr48chev · 03-14-2023, 01:03 AM

Here we go again.

You need a cast iron V8 (or the bellhousing that came with the 292 bellhousing to go with the 292. AS long as that bellhousing is a manual linkage and not a hydraulic linkage. You may need a 55/59 V8 bellhousing.

You take the forged clutch fork out of the stock bellhousing and put it in the V8 bellhousing. That lets you use all stock clutch linkage.

The big rub is that the 47/54 crossmember under the bellhousing is different than the 54 and later bellhousings and you either have to modify the crossmember a bit for the mounts to fit or you have to find a 54 crossmember and swap. When I bought my 48 in 1973 it had a 194 in it with a V8 bellhousing and the stock closed drive train. They had modified the crossmember with a torch and a stick welder and it wan't pretty but held up with the 194, then the 283 that I put in it. I've got a 54 frame under the truck now because my original 48 frame had a big twist in the back from the guy who welded in my rear suspension welding up a whole side at one shot without letting it cool.

These weld on axle seats are designed to locate an open drive axle in the correct spot and at the correct stock height. The cost has doubled in the past year but my guess is that one can take some 1-1/2 thick wall rectangular tubing (real thick) and fab thier own fairly easily. Especially if you have the old closed driveshaft axle there to measure off and design with. https://www.classicparts.com/1947-54...ctinfo/93-317/

The hardest part of the swap is going to be figuring out exactly what you have to do to modify the crossemember.

I've got a 51 or so GMC long bed 1/2 ton frame for my stretch cab. you can see the middle crossmeber. I am thinking that when I pull the 250 and 3 speed out of the old frame I'll take a piece of cardboard and trace the shape of the 54 crossmeber and see what it takes to transfer that shape to the new frame.

I'm going to use the rear springs out of a mini van that I have that is currently a storage shed with wheels. It's time for it to go down the road to the scrap yard after i take what I have stashed in it out.

03-14-2023, 01:03 AM	#10
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,388	Re: 1951 GMC Floor High Hump Here we go again. You need a cast iron V8 (or the bellhousing that came with the 292 bellhousing to go with the 292. AS long as that bellhousing is a manual linkage and not a hydraulic linkage. You may need a 55/59 V8 bellhousing. You take the forged clutch fork out of the stock bellhousing and put it in the V8 bellhousing. That lets you use all stock clutch linkage. The big rub is that the 47/54 crossmember under the bellhousing is different than the 54 and later bellhousings and you either have to modify the crossmember a bit for the mounts to fit or you have to find a 54 crossmember and swap. When I bought my 48 in 1973 it had a 194 in it with a V8 bellhousing and the stock closed drive train. They had modified the crossmember with a torch and a stick welder and it wan't pretty but held up with the 194, then the 283 that I put in it. I've got a 54 frame under the truck now because my original 48 frame had a big twist in the back from the guy who welded in my rear suspension welding up a whole side at one shot without letting it cool. These weld on axle seats are designed to locate an open drive axle in the correct spot and at the correct stock height. The cost has doubled in the past year but my guess is that one can take some 1-1/2 thick wall rectangular tubing (real thick) and fab thier own fairly easily. Especially if you have the old closed driveshaft axle there to measure off and design with. https://www.classicparts.com/1947-54...ctinfo/93-317/ The hardest part of the swap is going to be figuring out exactly what you have to do to modify the crossemember. I've got a 51 or so GMC long bed 1/2 ton frame for my stretch cab. you can see the middle crossmeber. I am thinking that when I pull the 250 and 3 speed out of the old frame I'll take a piece of cardboard and trace the shape of the 54 crossmeber and see what it takes to transfer that shape to the new frame. I'm going to use the rear springs out of a mini van that I have that is currently a storage shed with wheels. It's time for it to go down the road to the scrap yard after i take what I have stashed in it out. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.