I’ve worked on a lot of differentials – but unless one snuck in on me without me noticing, I don’t recall working on a ’69-70 or ’71-73 B-body 8¼” – so I don’t know about part interchange.
I do know that if a person is going to build (or re-build) a differential, you might as well put a limited slip carrier into it at same time.
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According to
1969 DODGE CORONET Auburn Gear High Performance Series Differentials 542072
The carrier will only fit 66-70 8¼” differentials.
Note: I have never seen an 8¼ in ’66, ‘67 or ‘68 Chrysler product – and I’ve seen a lot of differentials.
Further research shows the carrier bearings only fit ’68-70 8¼ differentials – so I suspect the carrier bearing size is what the whole hiccup (limited usage) is about.
1969 DODGE CORONET Dorman Ring and Pinion Sets 697-356
The Ring & Pinion gear set shows to fit from ’65 to ’76 8¼” only – which tells me two things.
The carrier bearing size is what is the limiting factor is on the carrier.
The length of pinion gear (or bearing size) is also a limiting factor on that, as well.
As a whole differencial, I think you are good.
As far as swaping parts, I don't think you are going to get what you desire.
BudW