464, Duck Lake Rd is the easy, straight and flat route from Browning to Babb and St Mary.
Years ago I stayed at the St Mary KOA in Sept without reservations.
I haven't driven it, but 49 between E Glacier and 89 appears to have zig-zaggy ridge crossing at the north end.
Yes, 89 is twisty enough to be tiring at the end of day even in a car. According to the state dot, they are finishing up widening and straightening some of this. It is the main road from the east into the park.
Google street view, the underpass on 49 right off of 2 is signed at 13', (12'8" in a newer photo)
