replaced control arms with Dorman pt #524-197. sez its correct fitment but unable to align rear wheels, seems its to big? Mechanic sez its the right replaced part judging by the old one... the online shop sez its the correct part, the alignment shop says its the wrong fit. too big?

It's possible. Only the 00-09 Legacy/Outback/Baja uses that style rear suspension, and they all use the exact same arm. So I think the only explanations are that something else is out of whack, or that that piece isn't right (presumably a fluke, Dorman's usually decent). When it comes to a toe adjustment, they have to be very precise, as little as 1/4" can be a huge problem.

 

 

I just measured a new OE one, and it looks like 10 13/16" bolt center to center. Probably impossible to get an accurate measurement on the car, though, as those bushings need to be completely unloaded.

 

 

FYI, OE number is 20250AE06A.