There are tons of them around, you just need to know how and where to look for them.
GMC 302s were used from '52 on in 450 series trucks. They will have a serial number on the doorpost ID plate that will read something like 453-30-12345 as an example. The two middle numbers, 30, indicate 302. If the middles numbers are 24, its a 248, 27 - it's a 270 and so forth.
Civilian 302s are harder to find than the sealed military blocks which to me seem pretty plentiful. Converting a military block is a pain in the rumpus because they were sealed and many of the accessories and the HydraMatic transmission (these are the only way military 302s are offered) along many other parts are useless and require parts searching when you use them in a hot rod or civilian application. I just finished converting a military 302 and it is running in my '51 6 volt positive ground 3/4 ton Huckster. Goes like the wind and it's pretty much a stock motor with some hidden upfits and tweaks. Nothing crazy.
GMC 270s are VERY plentiful and were used in everything from military trucks during WW2 and in civilian trucks up to the early 60s. You'll find them in medium duty trucks from 47-59 and in light duty (pickups) from 55-59. They are a great motor sporting the same stroke and slightly smaller bore as I'm sure you know.
We have a "WANTED" section on our
oldGMCtrucks.com forums pages where you can post an ad for whatever you want. We are GMC freaks and have over 2800 eyes looking all the time so we know where a lot of bodies are buried.
What section of the country are you in?
