70 c20 help

[Randall04]

What's up guys & gals! I recently got two trucks off my uncle; one is a 76 c 20 with 84,00 origional miles. The body is really rough, but mechinacal is good. The a/c still works! The other is a 70 c 20. This is where my intrest is. How can I tell what size engine is in it, without pulling it. It's a SBC with a 1 barrel carb, and the oil filter looks like a cartridge filter inside a chrome canister mounted on the passenger side inner fender well. It's got a granny 4 speed trans. Where can I find reasonable body parts at? I already know of LMC from my previous project 86 truck. Thanks for any help!