I bought a 73 Duster about 3 months ago, swwet car, had some mechanical issues which i was ok with, car is mint. had a bad tranny, no 3rd gear, 904. pulled the 904 and swapped in a 727 with goodies. 360cid. new intake, valve covers new cam, timing chain gears, dipstick. has a 69 8.75 rear end was making tons of noise, 741 case:(. had 391 in it and was so loud it was defening inside the car. no fun to drive. picked up a new set of 3.55 gears, and bearing kit. the pinion gear is wrong compared to what i pulled out. the new one has fine spline count and the one i pulled out has like 6 splines on it, this was repaired once by a tranny shop and it was never quiet. is it possible the put 742 case parts in a 741 case? the carrier bearing part numbers on the say the fit a 742 case. the install kit says it s for a 741 case and according to motive gear, the ring and pinion fit a 741 case. gear p/n is C887355m and it install kit is P/N rat-351K. any insight would be appriciated.