From 285, we drove to the top of Marshall Pass in my stock explorer. There is packed snow on much, but not all, of the road once you start heading up to the pass - more the higher you drive. Most 2WDs could probably get to the Marshall Pass TH (about 200 yards from the actual pass), but the snow the rest of the way wasn‘t quite as packed down.
There were tracks going down the other side of the pass, but we did not follow them.
Pic is of the road in the flat area leading up to the Marshall Pass TH. Pic was taken on the way down.
Photos (click for slideshow):