Motor went in my 1990 range rover and the local junkyard has several discos to choose from but only 1 Range of the correct years. None of the trucks have keys or batteries So I wont be able to see what runs and what doesn't. They do have a warranty on used motors but it only applies to exchanges so if the 1 Range motor is junk or I take a look at it and it seems like its trashed I want to know that I will be able to exchange it for another motor out of one of the discoverys. I'm guessing that as long as its a 3.9 I should be able to swap them no problem but I have not been able to find a definite answer on this. Not to mention that it is alot of work just to find out if it runs or not, Id rather just pick the potentially best motor out of the bunch to start. Any suggestions would be greatly appreciated, By the way if anyone has a running 3.9 they want to sell in the Mass. area for cheap please let me know!