The only work I had done by someone else was done by a shop in Green Bay called Performance diesel because I was working up there. They did very good work and love the PSD. Well, I also took it to a fairly large diesel shop in Allenton once, whom I won't name, but it won't be going back there again. The guy who owns the place is really good, but he has people working for him who just don't care.
When I need help on my truck, I take it to a small one man shop in the middle of nowhere called Bob's auto repair. I have known Bob my whole life and he was a Ford diesel mechanic for 25 years before starting his own place. He works on a fair number of trucks and actually used to have a pulling truck for a while. He doesn't work fast since he does all the work himself, but he is very honest and knowledgeable, and he doesn't charge an arm and a leg.
I have heard some good things about Hucksdorf and have seen their facilities. They work on lots of diesels. Another option might be Badger Truck Center downtown on St. Paul Ave. They always have lots of PSDs in there.