I picked up a 2.65 rear end from an 81 450sel to transplant into my 123 wagon. I figured I would split the difference from the 2.47 and 2.88 (right now I have the 3.07 unit. The cases look a little different but so far all of the mounting points seem to be in the right places. It also "seems" like the axles will interchange. Has anyone else swapped to the 2.65 ratio? How do you test a used diff to make sure it is solid without actually installing it? The car I got it from only showed about 100k miles but there was not alot of oil in it though there was oil coating everything, when I opened it up (I think/hope the picnpull yard drained it).