What’s the going rate for one these days ?
Got one with shafts sitting in garage that I’m never going to use.

At a very big guess over 200 pounds
G

My perception is the home build market is disappearing & what hasn't disappeared has moved onto using MX5 or BMW diffs. 10 to 15 years ago i think it was worth a lot more than it is now unfortunately (says he with a 7" diff under a workbench).

I have the 3.14 without an LSD. Could the internal LSD be swapped over?

Not certain but the crown wheel & pinion may fit the lsd.

They have dropped dramatically in price (percentage wise, value is perception dependent on wealth).

I have sold 2 this year.

A 3.92 open diff went for £100, probably paid around £150 around 5 years ago
A 4.27 open diff went for £180, these are super rare and I hunted around for this "luckily" only paying £250 for it about 5 years ago.

If its a sierra LSD the Crown and pinion do swap across from memory. It is something I was looking to do. Requires a full rebuild unless you have to tools and knowledge. I would recommend Road and Race near me in north kent. It would cost probably £325+VAT to fit an LSD in swap C+P and rebuild the diff with all new consumables.

Good luck with the sale