A few of the concrete storage buildings remain, as well as, some of the concrete foundations. Some of the houses were moved, possibly to Fort Keogh. I really enjoyed using the 'paved' road when we were conducting research in the Radar Base Pastures from 1994 to 2006.
I was stationed there in 57-58. That is correct what the others have told you about the exit. For history, pictures etc. go to this link http://www.radomes.org/museum/ On the left side of he page click on RADAR SITES. On the next page type in 902 where it asks for Unit/Squadron. On the next page click on Miles City AFS. On that page you can click on the site roster and all of the other stuff below that. Look around. Three of us walked in to the base in 2004 and there isn't much there. The AF did a poor job of cleaning up. I understand now that I climbed the fence to get in that you can borrow a key from the manager of the Experiement Station that will unlock the gate and drive in. If you go now be carefull. Rattlesnakes. We had them in our barracks. Some fun stories.