Mopar only Borg Warner T-10s used a trunnion joint for 1963 model year. 1964 New Process 833 trannys still used the trunnion. That's all that was the same..
The T-10 was built very specific for a mopar bell-housing. Also mopar T-10s have longer tail shafts than their GM cousins.

so with the little info you provided, I would say it's a May or June built '63 but what one, A or B-body?