Moparts Tech Archive
Rearend Comparisons by DoctorDiffInfor Provided by DoctorDiff
Notice, all pinion shafts neck down to the same diameter at the front bearing area.
Contrary to popular opinion, the 489 case does, in fact, have a 90 degree stress riser just like the 742 case.
Notice, the only pinion that does not have a stress riser in this location, is the 741 case.
Notice, the popular Ford 9" uses the smallest pinion shaft of the bunch.
For comparison, the Chevy 12 bolt truck, has a pinion shaft diameter 0.060" larger than the 741 case.
Note the factory installed solid pinion bearing spacer, found in all 741 cases.
Also contrary to popular opinion, the 489 case uses a smaller rear pinion bearing than the 742 case and the Dana 60.
I included the common M88048 rear pinion beaing found in most 9" rears. Even the Ford "Daytona" style rear pinion bearing is smaller than the 741 offering. Admittedly, the Ford 9" also uses a pocket bearing to support the end of the pinion.
As you can probably tell from this post, I consider the 741 case 8 3/4" to be highly underrated when compared to other more popular "performance" ring and pinion designs.