4-bolt blocks

[zac]

I kind of hate to rehash this old subject, but I want a little input. Here's the deal:

I'm getting an engine rebuilt for my '70 K10 burb. It has the optional 350, it's still in the truck and I'm not pulling it out until the new one is built. I think it's an actual '70 motor, but I can't be positive. I have a 4-bolt block, the usual 0010 truck block that came out of my '72 K10 burb. I also have a '74 3/4 ton Chevy van that has a 0010 block, LS9 option code 350 in it. It has the little oil passage plug in the top front area of the block that is usually a good indicator for a 4-bolt block (although I've seen 2-bolt blocks with it as well). I know for a fact the van has the original engine. It has been in my family since it was new.

I would like to use my '72 block for my '70 burb, but I still want to have a 4-bolt block around to use later for a Vortec 383 build for my '79 K20. I feel fairly confident the van is a 4-bolt, and probably the engine in my '70 as well. But I know from experience there's really know way to know other than actually pulling the pan. But the crossmember situation on both trucks is going to keep me from doing that. Anybody know any other indicators for 4-bolt blocks or have any input?