55.2-59 55-59 Chevy chassis vs GMC chassis.......interchangeable or big differences?

[NW Task Force]

I am currently looking for a 55-59 Chevy 1/2 ton short box chassis/frame. My question is: Can I use a GMC chassis of the same year span and will the chevy parts bolt right on? I'm mainly concerned about using a chevy core support on a GMC chassis.........a GMC core support & brackets maybe different?

If anyone knows for sure, i'd love to know so I can determine if I need to stick with a Chevy chassis or if GMC is another option.

Motor mounts are not a big deal to me.......I plan to use an aftermarket small block chevy motor mount kit that bolts from the side (frame channels). It's the radiator core support brackets I'm worried about.

[58CameoAZ]

Gmc & Chevy are a different in the core support and frames are different in the cross members. Close, but no Cigar!

[dsraven]

take a look in the assembly manual for frame drawings but I know the gmc sometimes has a different support than the chevy. I think they bolt up the same to the frame but the sheet metal is assembled differently for sure, more like the AD trucks with a surround made up of smaller pieces instead of a rad that bolts to the backside of the support.
the 58-59 frames are different out front of the spring mounts because the front sheet metal is longer and the bumper has a filler behind it.
I started with a 58 frame and ended up putting a 57 front sheet metal clip on it. the 58 had the same rad support brackets as the 57 but they were further forward on the frame. my 57 gmc was a canadian model and used the chevy rad support.


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

[dsraven]

what is the reason for a new frame, if you don't mind me asking? looking for a leaf spring front end instead of a clipped front end?

[NW Task Force]

Originally Posted by dsraven

what is the reason for a new frame, if you don't mind me asking? looking for a leaf spring front end instead of a clipped front end?

Originally my 57 shorty frame was all stock when my family bought it in the early 90's. Later a 1977 camaro subframe was grafted on around 2000/2001 by a friend of my dads. The truck stayed dormant until 2013. I took it over from my dad and reassembled everything on my own. I discovered that the clip job was not geometrically straight. The welding on it is great, but somehow the alignment is off. The engine does not sit straight in alignment with the radiator and my local tire shop confirmed my findings that front wheel alignment had to be adjusted grossly on one side. Bottom line: It's not right, and I don't want to deal with fixing it.

My real goal is to build a "NAPCO style" 4x4. I recently scored an original 1955 2nd series short box 1/2 frame that is complete. I basically want to build something very similar to what OrrieG built. Going 4x4 is a great way to keep the stock frame intact and have the ability to "bolt-on" items. My next thing is to find a 70's era K5 or K10 that is somewhat complete to use as a donor rig.