7 1/4 to 8 3/4 swap question about driveshaft length

my 1967 dart factory service manual shows a 6 cyl with a 7-1/4 rear end has a drive shaft length 54.61.
the 273 with 8-3/4 rear end has drive shaft length 52.58 BUT i dont know the the difference of the trans length. or if the back end of the engine being in the same place. both for manual 3 and 4 speed and auto trans.