Well that is a good point and forgot to mention ive been a chevy guy my whole life. Iv heard of the 390 but not the other two. Any way to tell off a casting number? I can tell you im not going to pull a head to find out. The car does run good and seems to make good power after 20/25. Its just the inital stomp of the gas from a dead stop and the rpm's just dont come up real fast