What's in a factory K20 setup?

[backwoodsK20]

I just bought a '68 Chev 3/4 ton 4x4, it has an inline 6 (guy says it's a 292, could be a 250...), and a 4 speed. The rest of the truck is untouched, all stock. So, lets begin...
- What's the external difference between a 292 and 250?
- How is strong the transmission, compared to the SM465?
- How good is the transfer case? I assume it's a Rockwell from what I gathered.
- Did the diffs come with posi or a locker from the factory, and what gear ratio would they likely be?

I don't actually have the truck yet, I still need to pick it up, so I can't really go out and check for certain details right now.