This is a crosspost but I don't think anyone in the transmission forum has the answer to this...

I need a new rear driveshaft for my 2.5RS 5MT into 4EAT 2.5L Legacy OB swap. I live in Cleveland, and I see three for $55 in Pittsburgh, which is by far the best price around. I also happen to be in the area on Wednesday. I talked to someone at the junkyard who was convinced that standard Legacy and Legacy Outback driveshafts were different. He said that the ones he had were all from 5MT Legacies (non-OB) and that because they were probably 2.2l engines, they would not work with the 2.5l in my Outback. I couldn't believe this. Will these work on my 2.5l with '98 RS 5MT tranny or not?

these seem to be different on some models & rear diffs. the rear flange though is removeable on the diff end, & an appropriate flange can be bolted on to fit the driveshaft.