[TR] TR6 differential

[David Soknacki]

Fm   David Soknacki
     74 TR6 CF22072U
 
Two years and 8400 miles ago I replaced my very loud differential with one
that I bought 'as-is' for $200.
 
Until last month it worked well, but now there's a loud 'clunk' every time
the drive train is engaged. Even worse, I have a cracked frame near one of
the nuts holding the differential.
 
I don't see any choice about getting the frame welded.
 
But what about the differential? 
    Do I find another 'as-is'?
    Or do members recommend getting mine rebuilt? Is the going rate really
about $900?
 
Any advice welcome.
 
Thanks so much.