The Stovebolt Site Forums The Shop Area Engine Shop 55-59 Chevy/GMC chassis identical?

In the Task Force era GMC and Chevy 1/2 ton trucks, are the front crossmembers the same?

I want to mount a period correct 283-V8 in my GMC chassis using the original type chevy front mounts, but then it occurred to me that the GMC motors were longer than the chevy and that the front crossmember may be different. I'm pretty sure that was the case on earlier year trucks anyway. Does anybody know for sure about the TF trucks?

Red58? You're very knowledgeable, any idea?

I have a '58 Chevy and a '58 GMC, but unfortunately they are not both in the same location so I can't compare them side by side.

Thanks.

The frames should be the same. The difference is in the mounts that are bolted to the engine. You should be able to use the v-8 kit for a Chevy with no problems.

gmc crossmembers were completely different than chevies. The 6 and 8 cylinders used the same crossmember. there was an extra plate riveted to the v-8 crossmember for an engine mount. I believe the gmc 8 mounted under the balancer to the crossmember. you can swap crossmembers by drilling out the rivets. Even with the gmc crossmember, it should be a pretty straight forward swap. blue chip crossmembers are the same for 55-57 and 58-59. the 58 and 59 are eazier to swap because the radiator and front sheet metal do not mount to the crossmember like they did in 55-57 models.

OK...it looks like I'm in for a crossmember swap. With patience and a big hammer, I'm sure I can get 'er done. Thanks bigbad. I looked at the GMC crossmember yesterday and it looked different that I remember the Chevy crossmember being.

Are the Chevy 6 and 8 cylinder crossmembers the same? Or do they have extra plate riveted on as well?

I think the chevy crossmembers are the same for 55-59. Don't know for sure... never had a chevy. I thought the chevy used the donut mount and had two sets of holes, the closer set for the 6 cylinder, and the wider set for the v-8. Don't know for sure.

Only know about the gmc crossmembers because somebody had welded a chevy one in to my gmc chasis and put a chevy 235 in there. I had to locate a 58-9 gmc crossmember, and I had to cut the chevy crossmember in pieces to get it out. All that for a truck I ended up getting rid of before I put the 302 gmc in it!

I really don't think you need to swap crossmembers. I think you could probably set the engine in there and drill the holes where you need them in the gmc crossmember. my .02

Getting the crossmember out is the easy part. Trying to get it back in is the hard part.

If you do go for the swap, Get a lot of patience, a big hammer, and a couple heavy duty ratchet tie downs. The frame has a tendency to open up just enough so the rivets or bolts won't line back up. Good Luck!

John

yes the Chev cross member is the same for 6 and v8, except if it had a v8 then there were 2 brackets riveted to the back of the cross member to mount the v8 [cuz shorter than the 235] - the kits available from the vendors that's called 'original style' v8 mounts includes the frame brackets that you bolt on [rivet holes should be present], along with the pegs and small brackets that bolt to the front of a small block - you'll also need a fan shroud or it'll overheat at low speed cuz the fan's too far back

and yes, I think the cross members are too different to work installing a 283 the same way in a GMC - you could use whatever the GMC v8 was for 58 tho!!

Bill