I am applying inside Canada, but they want me to get a stamp on my passport to prove entry date... but don't have one. i have been here since jan 2010, way past the 6 months allowed . so do i drive back to Montana stay a few days and come back into Canada and ask for a stamp on my passport? the question is, does the border know how long i have been here? and will they let me re-enter?
So, you are a U.S. citizen over stayed in Canada. As many U.S. citizen travel to Canada frequently because of close border that's why border police sometime don't stamp the passport.
The border police don't know how long you had been staying in Canada.
If you can drive back to Montana and when you re-enter ask the border police to stamp your passport this time. Sure they will let you enter. I don't see a reason,why they can't.