8.75 help

[master4x42]

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.

 

[master4x42]

pic of car

 

[Duster346]

is it possible the put 742 case parts in a 741 case?

Carrier yes, ring and pinion no.

If you did in fact get a 741 gear set, for your 741 center, which it sounds like you did, all you'd need is a fine spline pinion yoke to replace your coarse spline yoke.

Majority of the noise can be blamed on improper pinion depth.

Hope this helps some, let us know how you make out!

 

[master4x42]

alright, it is the correct gear set with a 29 spline pinion, so a new pinion yolk is in order, the carrier bearings look to be in good shape, and the pinion depth is way off, so i will probably reused the old bearings since they seem to be in good shape, but i will use new pinion bearings. the old 3.91 gears are totaly shot.