The Stovebolt Site Forums The Shop Area Engine Shop 55 2nd gmc 3 speed compatable with a 350?

Ok, here I go again... since my original 248 was damaged from water and rust, and Id rather just get a 350 engine in it rather than pay big bucks to have the 248 rebuilt, question is could I install a 305 or a 350 in my truck and get it to bolt right up to my original 3 speed column shift type transmission? I have a 55 2nd series gmc with a 248 inline six mated to a 3 speed. I just want to drop the engine off at the dump and install a modern v8 in its place... but id like to use that transmission, linkage, and shifter if i can... any help would be appreciated... thanks

Hy GMCUSTOM, first put the engine you don't want in the "FREEBIES forum", we don't like to see parts for these old trucks taken to the dump! As for the 350 swap, it is almost a drop in, and the tranny will be compatable. GMCs V8 was a Pontiac, but the Chevy 350 can be swapped in fairly easily using mostly factory parts, hope that helps.

I think that you must have misunderstood my post... I am taking out a 248 (a gmc inline 6, not a pontiac v8) and Id like to put in a 350. I have an inline 6 gmc 248 connected to a 3 speed stock tranny... i dont have a pontiac v8

Hy GMCUSTOM, I think you misunderstood my answer, I realize you are removing a 248, I was telling you that the V8 that GMC used in its light trucks was a Pontiac, not a Chevy so the swap to a Chevy V8 in a GMC is not quite a drop in, hope that helps.

3b is correct. The '55-'59 GMC used a Pontiac engine in their V8 powered trucks, rather than a Chevrolet engine. You will need to find the correct engine mounts and bellhousing for a Chevy ('55-'67 will work, exept for '60-'62) to make the install work, GMC parts will not be compatible with a Chevy engine. The trans will work just fine, though. You will also need to source out the correct linkage for the first/reverse gear. The linkage is different between 6 cylinder and V8 for '55 (or at least it is on Chevy). There is a bellcrank that mounts to the bellhousing on 6 cylinder models that is not used/present on the V8 bellhousing.
As far as junking the old engine, what 3B was trying to say was to offer it to someone that can overhaul it, rather than just scrapping it. There's most likely someone out there looking for a good original engine for a restoration. Or even a rodder might want it. We'd much rather se that than it just get scrapped.

So my existing 55nd series gmc 3 speed tranny will not connect right up to a 350 chevy engine? Ill need a special adapter of some sort?

The trans will bolt up, but you will need the correct bellhosing and shift linkage. The 6 cylinder bellhousing will not bolt up to the V8 engine. The Chevy V8 bellhousing shouldn't be hard to find, same one was used up to the late '60s. A good sorce for one is to look for Low Cab Forward (snubnose) trucks at the salvage yards. '55-'59 those trucks came with a V8 as standard equipment.
The rod for the linkage could be made easily if you can't find a correct V8 one or one from a '56-'59.
You will also need to come up with front engine mounts, either the factory style front mounts, or the universal style side mounts.
The swap can be done, you just need to have all the correct parts on hand to do it.