How to tell which motor I have

[68_Step]

My truck is new to me, and the guy I bought it from told me it had a 350 in it. I did not really care which motor it had in it at the time, I just concerned myself with how it ran (great). Which set of numbers on the motor will tell me what I have? The one on the passenger side front of the motor (stamped in I think)? Or the one from the back of the motor passenger side? Will I be able to see the one on the back without pulling the motor? All I am sure of at the moment is that it is a V8 with a 2 barrel Rochester.

Thanks!