55.2-59 This ole girl followed me home

[dsraven]

motor mounts look like the quick and dirty style. possibly the cross member used in the truck is for a GMC and may be a little different than the Chevy. I have had both Chevy and GMC with a 6 cyl and 3 on the tree and both were apparently the same. Canadian models though.

https://www.trifive.com/55-59Assy.pdf

[dsraven]

check engine section around sheet 25 for engine mounting instructions. dimensions are in the frame section.

[1project2many]

GMC and Chevrolet use different crossmembers in the US. Top is a 57 GMC, lower is a 59 Chevrolet.

[jmlloar]

Definitely looks like chevy engine rigged into a gmc frame.
You cant go by Canada stuff their gmc's used chevy engines and U.S. had gmc 6 cyl and Pontiac V8's.

You could swap to chevy crossmember but to do that you have to swap rad support also since the gmc support mounts to the crossmember and chevy mounts to tabs on the frame. Again Canada stuff is chevy parts there also.

I used a 14 bolt semi float in mine from a 99 3/4 ton. All I had to do was knock all brackets off the rear. It had same tube diameter and same joint size. Since the gmc stuff was bolted on I just had to weld perches on and rest fell into place.

Driveshaft shortened a little since rear had a slightly longer nose.
3" total wider. Only 1.5 on each side.

Now I got 8 lug rear with easy to find parts including brakes and 3:73 gears all in one package from a donor truck that only cost a few hundred for complete truck.