I doubt you can determine what car a 66 block came out of unless it was in a 68-up car and has a VIN on it. There were a LOT of 66 blocks cast that were used in 66-67-68 cars.

The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!