My 54 is set up as a tow truck but the tow body configuration looks more sixtys era.The fellow Igot it from had inherited it and only knew it was supposed to be an orginal engine and refered to it as a Big Block which I had figured to mean a 235 instead of a 216. Now the posibility of a 261 enters the picture Got the serial number off engine 0106411T547 but haven't located the casting numbers yet. I know they are lurking under the grime somewhere.