Thanks all! Contacting the Ranger would be a good idea. They've had a lot of rain this spring so washouts on the road are a good bet.
The reason we're here to begin with is because of Best Friends Animal Sanctuary. We volunteer there twice a week during the month of March. Even if you don't want to volunteer, the tour is well worth the time. BF is a very unique and magnificent place!
We have ATVs with us this year. We may consider taking them instead of driving the GMC. Kind of depends on the condition of the road. All good advice from you guys! Thanks!