wll an 80s truck 4 spd tranny fit an a body?

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i don't think so, the a-body A833 and A833OD trannys were model specific. regular and OD units had different front bearing retainer sizes, not a big deal if you use the same bell and use the correct shift fork or use a hydraulic TO bearing. but the tailshafts for only A-bodies had one shifter mount boss behind the trans mounting point, others had two different shifter bosses in different locations. thats a bigger problem.. not sayin it cant be done though!!
start by identifying what trans you have.
i'm sure theres more to add but i'm still gathering info for my auto to 4speed swap also.
good luck !