help me date code these 727's

SGBARRACUDA said
The 2466900 on the 2 BB trans is cast right on the side just above the shift linkage on the curved part of the case

Probably the P/N (or C/N) of the trans case itself. The case is not called out in FPCs, but there are a lot of 2466 *** parts in PTC 21-03-0 (Transmission Case) in '66 and '67.