Need pics of the teeth on the crown wheel & pinion to see the ware marks. That will show if its going to be quiet when you put it back together.
VS , I would go for the diff with the chain wire. I have replaced several pinion seals on diffs when fence wire twisted around the yoke & destroyed the seal. Just did the pinion nut up 1/8 turn further than it was before I undid it. Have done it most recently on on 123 & on a Dana 35. Both have crush washers I didnt replace.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving