transmission casting numbers?

[slx70]

I am changing over to a 4 speed in my 1970 340 dart, I bought a transmission last week and am trying to figure out what year it is, and what it came out of. Can anyone help?

cast numbers main housing C99129 H
tail housing C99126-1
stamped numbers 1B200907
P8833331 0095
Thanks.

 

[jtkaaa07]

Don't know what it came out of, but build date is Sep 10th 1970