98 with 153K miles but bad front diff

[amadrid]

So I was all set to go take a look at a 98 for sale. Seller wanted alot but was on vacation at the moment. Upon return the seller said that the front diff has to be replaced. Didn't get a quote on replacing though. Overall the rig looks clean on the inside. Outside seems ok but i dont know about the rust. Seller now has been dropping the price and is asking $6,000 for it. Im in Hawaii (Big Island) so costs to fix are likely to be high.
Is this one a walk away or worth taking a closer look?

 

[Trapper50cal]

Depends if you can find an 05/2000 to 07/2002 front diff donor rig on the Big Island. I have to imagine shipping one from the mainland might be cost prohibitive. 01/1998 to 07/2002 all have the correct gears (4.30's) but the the 89-99 diffs are 2 pinion vs. the 2000-2002 which also has the correct gears but is a 4 pinion front diff, which is superior. No sense putting in a 2 pinion unless it's the only thing available.

Here is the most specific data on the front diffs that I got from Cruiser Outfitters (to the best of their knowledge):

01/1998 thru 07/1999 is a 2-pinion 4.300:1
05/2000 thru 07/2002 is a 4-pinion 4.300:1 though we have seen some 2000's with the 2-pinion as well, likely left-overs utilized.
08/2002 (model year 2003) thru 07/2007 us a 4-pinion 4.100:1

And I believe this data is North American Domestic Market specific.