I have a 727 that I bought as a core to rebuild several years ago. The guy I bought it from thought it came out of a 70 E-body. I am going to rebuild it, but the parts book shows a change in 727's in 72. How do I determine the year that the trans was built? It is stamped K3515845L 3338 8707. The L could be a 1.

74 Challenger, bought it new. In 1978 I replaced the original 318 with a 446 and 727. Mild cam, Jardine headers, and Holley Sniper EFI.
New engine! 511" RB, Edelbrock Performer RPM heads, Eagle rotating assy, Comp hyd roller cam, Doug's 2" headers.