Rearend 7.25 junk????

That cone type SG is rebuildable
But you see those shiney swirl marks on the case? Those ain't supposed to be there,lol. In all probability, the pinion bearing is or was at one time, loose.
I have run RGs with chipped teeth for many years.

In a proper application a 7.25 with a SG will take a good deal of punishment.