west yellowstone to Polson

thank you for great suggestions! plan A is to go 287 BUT because we will have gotten gas in Rawlins on way to Grand Tetons and Yellowstone, and doesnt seem to be another place for gas between thos areas, via 287 til Butte, we thought, depending on gas mileage (we do have 100 gal tank) we have plan B going up 191 to get gas in Belgrade,we will see....never been the route Im relying on google map and my FMCA map that tells me diesel gas stops for our motorhome.