the " 'C' means powerglide build in cleveland" has to do w/ the vehicle VIN number, not the part number - if the trans is most likely original and looks like the one in the manual, and the manual sez it's a M23 ....... what was the question?
the C174
might mean M23, but I'd expect it's more likely a date code like march 17, 1964? not sure how they were dated, but they were - the 383 number is the trans case casting number, and they were all stamped exactly as they 'should have been', even if not quite legible at times
Bill
