Thanks. I have just bought a block with casting number 3921970 to put into a '66 C-10. From what I saw online, that casting ran from 63-76. My suffix code is RE, which another website told me was from 1969. Sounds like none of this will present a problem as I attempt to piece the various components onto it and drop it in. Would appreciate if anyone has other data regarding this casting number and/or suffix code.
