Hello everybody

[tomsa]

i have a question about casting numbers on my chevy smallblock. ive tried several online sources for decoding and keep coming up with confusing answers, if any at all. the block is a 3970010, it has the pipe thread plug above water pump, and the threaded hole at rear under distributor. the casting number on the front under alternator is V0523CMU, im reading this as a 4 bolt main, made in flint, on may 23, but cannot find reference for what CMU means. i read that Cm means was for a 4spd originally, but i dont know what model vehicle it was in or hp rating, or how to find out. i have found no reference for what the "U" means whatsoever. Id sure appreciate any info you guys/gals may have ! Thanks