Pulled the 3rd member, axles are good, spider gear and center pin are broken. There's a 96 in the local junkyard but it caught on fire about a month ago. They're going to send me some pictures. How do i know if the gear ratio is the same as mine.

 

Unless they are aftermarket they are all the same. 3.54:1 for coil spring rovers and 4.7:1 for leaf spring rovers. Rover usually changed ratios in the transfer case instead of the axles.

 

I had a Detroit in my RRC. It was the single best mod on the truck. I had the duff rebuilt and replaced it temporarily with a regular open unit so I could continue to drive and it was a night and day difference. The only reason I don't have one in my current Disco is that I haven't decided how exactly I'm going to build the truck. What I'd really like to do is find the highest final drive ratio T/C I can and upgrade to 4.10's. That way I don't loose too much Hwy RPM but still have a low low end. I only want to buy this stuff once so I'm taking my time doing my research.

 

Replaced front and rear for $190.00 thanks to Paul Grant.

 

At least one of the diffs from it are probably good, you can use either the front or the rear. Depending on the mileage you might be better using the font as the wear will on the opposite side of the R&P teeth.
As said, all are the same ratio from the factory. You can compare the number of teeth to verify.
If they tooth count from the donor is 28/8 (unlikely) get them both because they are Ashcroft R&P and stronger, but you'll need to swap both front rear.

 

Pics of front and rear Diff's that got replaced... First pic is the rear and second pic is the front...

 

not pretty pictures at all, but i'll bet more front diffs look like, that than people know