Ok, I guessed that the engine I had rebuilt to replace my 78 2F was a 79, but I just checked the produciton date stamp on the DS block and it's a 75. What are the differences between the 75 and 78 and is one year preferable over the other for a rebuild? I know that my 78 had flat top pistons and the rebuilt 75 has domed/arch top pistons. I know this fact because the rebuilt engine was delivered to me with a cracked head that was subsequently replaced at the builder's expense - although it took them two tries to get a head that fit, the first one they sent was an incompatible year and didn't match the block - the pistons jammed on the head. I'm starting to wonder whether the head block combo that I have now is actually a good match, albeit the engine does run. Can anyone tell me how to date the head? The build is done and was paid for up front, so it's pretty much water under the bridge but I thought I was buying (and paying for) a later year (78) rebuilt engine. Also, all the engine ancillaries were swapped direct from the 78 onto the 75 (I was lead to believe the engine was a 78) and it's taken many trips to the shop to try and get it to run right. Problems seem to be stemming from the carb (rebuilt 78 aisan) but I'm wondering if the later year carb or distributer or any other components on the 75 block and who-know-what year head are also causing problems due to compatibility issues. ANy insight greatly appreciated