The 742 is stronger than the 489 cases are stock, if you replace the crush sleeve in the 489 it will last a lot longer under abuse than it will stock. It will still not be as strong as the 742 is due to the differences in the sizes of the front pinion bearing and the diamerter of the pinion gear shaft where the front pinion bearing rides

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)