I have 2 engines and 3 transmissions for my suburban. I'm pretty sure the one engine is a 57 model since it is from my donor burb and the other is a 55 model since it was in the back of the 55 when I bought it. Is there anyway of telling this? I'm trying to restore the 55 with as many original parts as I can.

Same goes for the transmission except there are 2 of them in the back of the 55.

Oh yeah. All of these are straight 6's and 3 speed.