Frankly, I'd see a diff specialist, and ensure you don't have to do the same job twice. The preload, backlash and exact check of the pinion to ring gear alignment is best checked with prussian blue. Up until 1971, all the earlier diffs have circular rebates for a turnknuckle to be inserted...to streach the housing a few though to allow the carrier to fit. Later, the process was eliminated.
The salisbury diffs are much harder to deal with than lift out 8", 9" and certainly the old Banjo Holden diffs. My mate had only Valiants, and he whent through five diffs on his Charger. He used Falcon 3.23:1 gears, then found Cortina 4 auto(3.5:1) and Cortina 4 manual (3.7:1) were best. His diff problems stopped when he got a mechanics ticket, and started doing it 'by the book'.
DYNOED250 said the later diff centre is the key piece.
From 1964.5 to the latest BTR/Dana diff in the utes, the case is the same.
The earlier case has very good axle extensions which don't break as easily as some of the later ones.
Dunno about bearings.
Some were crush spacers after 1977-ish, most utes were shanked with no crush spacer.
Changed from 25 spline to 28 happened around 1992 with the EB. Some are 7.625", others, including the first XP and XR diffs, were 7 7/8" crown wheels.
Issues are case clearance and the original crown and pinion bearing. Get the right bits, and there is no offset change, then you should be okay. With the 28 spline, the pinion offest may have varied, but the ring gear carrier sorts that.
