The HO52 and 72 differ in castings for center section. At least I've seen some relatively light looking ones and heavier ones with a screw to adjust and limit ring gear deflection under heavy load, presumably this is an HO52 and HO72 difference.
They will however interchange.
Brakes differ by vehicle model/size and also by years I believe. Brakes on a very late model HO 52 or 72 may be different than early model.
I'm not aware of an available direct replacement for just the drum on an AD 1 ton rear. Please post your findings.
As discussed in other threads and other forums you can swap and update the entire brake package on the old Eaton for brakes from a 14 bolt or aftermarket brackets and disc brakes, or make your own brackets and use very late model disc with park brakes (I'm doing this one).
But, at some point an entire 14 bolt is cheaper and easier, and easier to get any parts for down the road. Why swap gears and brakes on the old axle when the correct 14 bolt with those upgrades can be installed whole? (I'm also swapping in a 14 bolt)
Plenty to consider.
