US 89 going north from Browning to St Mary's Glacier NP

I do not have any recent first hand knowledge regarding these roads. Several years ago, I did drive MT 49 from East Glacier north to Kiowa. That sounds like the road you're describing. I think I read some posts this summer about the poor condition of US 89 and some folks preferred to drive north out of Browning on MT 464 to Starr School Rd, then west to US 89. As I remember, they felt this was a better road. However, I do not have any personal knowledge about it.