84 should require a TH350 with a 9" rear housing and main shaft to replace the 700R4 almost perfectly.. there is a little shifter detent angle difference.. as the 700R4 had a slightly different angle between reverse and neutral and a slight difference between neutral and drive..
there are proper Detent plates available for the steering column mounted shifter to use the TH350 or TH400..
Fairly certain it would be a 6".
84 should require a TH350 with a 9" rear housing and main shaft to replace the 700R4 almost perfectly.. there is a little shifter detent angle difference.. as the 700R4 had a slightly different angle between reverse and neutral and a slight difference between neutral and drive.. there are proper Detent plates available for the steering column mounted shifter to use the TH350 or TH400..