There is another big place just SE of Detroit Lakes also. I have not been in it, but past it. I have heard that they have a lot old stuff also. I don't remember the name right now.
There is another place up north that has '37's. I could drive there, but I don't know the name of the roads to take, it's up either #71 or #65, it's a small place and the guy that owns it works for the post office and some young lady sits there while he's at work.
we have driven all over the state looking for '37 parts and found a lot out there for them.

My wife pulls most of her parts, for her '27 "T" I bet I've been to the same antique shops!

Good luck.

Pat