engine build questions??

I just bought a 92 full size chevy truck. It originally had a 4.3 V6 but the previous owner put a V8 in it. He said it's a 350 but I'm not so sure. I've had people tell me to look on the back of the engine for numbers to run. I did find some numbers but the chevy engine codes revieled nothing. I found a website that has all the codes for chevy and it says to look right under the passenger side head on the front of the motor for three numbers. Is that right? Is there any other place to look that would tell me what size motor it is?

Did you check www.mortec.com? It's the reference I use most of the time. Gives you locations and number interpretations.

BTW, welcome to CHR. Lots of very knowledgeable engine builders here.

The pad that has the identifier is on the passenger side just in front of the head....it is part of the block deck that is broached flat for the head gasket surface. There is usually two lines of stamped numbers (not cast). There is a two or three letter sequence. From this, you can decipher several things about the original installation (but not always): the year, the body style, the carburetor, automatic or stick shift, and the horsepower.

The casting number on the back of the block on the top of the bellhousing identifies the part number of the casting only....it doesnt even tell if the engine is a two bolt main or four bolt main.

The Mortec site is an incomplete list but is better than nothing. A better list is available from MSA-1. IF you post the identfier, I have th MSA book that ranges from 1955 thru 1999 for codes and casting numbers

mike in tucson

Thanks for the help everyone.