tailshaft length questions?

1970 dodge dart swinger factory /6 3 speed column shift, looks to be factory trans installed in it guessing it is a muncie have not got my hands on a castin number as of yet due to the layers of dirt and grease on the trans.. tried putting a spectre 3 speed floor shifter and was unsuccessful the bracket hits the body reinforcement for the floorboard when attempting to mount it on the tail shaft bolts, the tailshaft has no shifter mounting bosses on it what so ever. will get some pics in the morning. I may have got the column shifter working will know when linkages are back in in the morning. the 3 speed has a 15 inch tailhousing length.

thanks sean
plano