The A745 “heavy duty” 3-speed came out in ‘61 and was offered in at least the ‘62-‘64 C-bodies with a floor shifter. That is probably what you have. It has weak synchros pins that are easily bent during hard shifts and that’s why they had the T-85J in the Max Wedge. A one year only MoPar T-10 was offered in 1963 before the A833 came out in ‘64. T85Ds were optional behind B block Dodges and Plymouths in ‘60 and ‘61.