SE Minnesota Dealers
Jon,
There are two dealers that I know of in the area.
Adamson's is in Rochester. 507-289-4004. Their diesel mechanical sat in a meeting or two of our fledgling chapter before it fell apart and seemed fairly knowledgable. I can't say for sure since I've never had any warranty repairs. However, the last time, and I do mean last, that I had mine in for a oil change, one of their rejects fractured the oil plug and ruined the oil pan. The truck was out of commission for a week waiting for parts to be trucked in (no air freight - right after the 9/11 attacks).
Marchant's is in Spring Valley. 507-346-7329. Small town dealer. I called them after the Adamson's fiasco as an alternative. The service manager came right out and said that they don't do a lot of work on diesels. Take that for what it's worth.
Let me know if you need any info.