Help ID'ing tranny/gauging interest

[camaro75racer]

I just bought an 86 Monte Carlo that had a turbo buick motor in it but also had a TH400. The guy said it was a Poston's tranny but i dont know and would like to know if there is a way to tell. Do they mark the tranny's? If so please let me know. Also if anyone is interested i will be selling the transmission. It's the buick bolt pattern and i have no use for it cause im putting a SBC in it. Thanks for any replies.
Dale