Externally, the 239, 292, and 312 Ford blocks are pretty much the same . As for the physical differences in a plastic model kit , virtually nothing. The differences in internals is however way different . On just the 239, ( offered on cars 1954, 55 ) , there is NOTHING that will interchange with either the 292 0r the 312 . O K , I'll concede the tune up parts , but that's about it . For what it's worth, "Most " Thunderbird cars by 1956 were built with 312's . Yes, 292's were built, used to work on one for a customer . His was a 1956 .