Iv'e got an 89 RS we bougt it without a motor and I was suppossed to start rebuilding the car...well I went to college so we ordered a crate motor and had it put in. GM sent us the wrong motor and the mechanic already had it in before we realized it was the wrong motor. I gave the car to my stepdad and he messed around with it for a while and now its mine again...and Im still not sure what motor it is. I can't seem to find the ID code on the block. I think its being hidden by the alternator bracket. If anybody could help me figure out what it is that would be awesome....we bought a full long block with heads and just slapped on the old intake and TBI from the original 305...the first time we ran into problems was with the water pump. Thats when I left the picture. They got it all put together and running but I don't know how...so before I can start modifing I need help figuring out what I got...If the number is definately behind the alternator bracket, I'm willing to pull it to look, I just want to make sure its there and I'm not wasting time.

Thanks
Birdman

 

On my 305 the number is on the back of the engine in front of the driver.

 

http://www.mortec.com/location.htm

Get #4 and ask a dealership to decode it for you.