Diff, do i fix? swap? or replace/upgrade

[old white 73]

Hi, spent Sunday changing diffs- the old one's making rumbling noises had looked at a u-joint failing again, they're sound but there's movement at the pinion flange. Slung 1 of my ugly looking spare diffs in & it makes the the same rumbling noise only much quieter than the old 1.

Can Avenger diffs be fixed or do I keep swapping diffs as I break them- have 3 spares left & I think only 1 of them is any good, or get something else under there, would like an lsd but my pockets aren't that deep yet (& it might solve some traction issues too)

[avengertiger]

pinion bearing? they can be fixed but its labour intensive.