1970 Muncie M-22 trans code ID help

[Ls6 Ragtop]

Jim,
Your transmission is indeed an over the counter transmission. CTO is the code used for complete transmission assembly for 1970 (the 0 after the CT is the year) and CC0 was used for replacement case i.d. in 1970. Your trans has the CT code and an assembly date proving it was sold as an assembled unit.
BTW I don't know of any documented Chevelle L78 cars with the M22 trans. M22 for the 396 motor was coded 3968012WM as was the Corvette and Camaro versions I've seen in 70. 454 Chevelles used the 3978766WO coded M22 in 70-71.
Hope this helps, Chris