How to identify a 292 from a 312?

[bullrunmotor]

Can anyone tell me if there are any external differences which one can use to identify a 292 from a 312. Someone told me ford only used 312 motors for automatic transmission applications. I've read you have to take the oil pan off and look at rod caps. Others have said engine paint was different color. Would engine block numbers tell the difference? I'm going to look at a bunch of motors and parts cars for sale and would like to figure out some method of identification. Thanks in advance