Fair Price for Jaguar Posi Unit & 3.54 Gears???

So I have come across a 70's posi/gear set. He's not sure of the year or what it came out of other than it's a series 1 suspension. The guy has the 3.54 gears and posi unit for sale as well as the 19 spline stub axles. I don't think I need the stub axles so what is fair for the posi unit and gears? It's in the shop right now having the internals swapped to a 30 spline setup. He said it looks like it was recently rebuilt as there are still marking for checking the gear contact. He is gonna send me pics when the swap is done.
Any advice on what is a fair price. Not much in the searches I did.

No clue. Hopefully one of our crossbreed experts will chime in... offroadrolls?

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Here's the photo of the diff before he took it to the shop for the rebuild.