The overdrives are factory wired so as to not to go into OD in reverse. However, 50 years ago I always wired my OD so it would work in reverse and they do not self destruct. They are a challenge to drive with the rear of the car steering. A friend of mine rolled a 55 Ford on straight road right in front of the drive in movie while he was going backwards in OD. Its about like driving a fork lift. I had quite a Few T86 BW transmissions with OD. The cluster and clutch gear went bad quite regularly which left me with no 1st or reverse. I still drove them in 2nd and 3rd until I found some gears. I just had to remember to park where I could pull out frontwards. The T85 and T89 were a lot tougher, but not totally bulletproof. I have about come to the conclusion that its impossible to tear up either a R10 or R11 OD as long as you keep oil in them. The hill holder was a Studebaker thing. It actually worked with the hydraulic brakes. It kept the car from rolling backwards on an incline while the clutch was depressed. I think other cars may have had a hill holder, but Studebaker really advertised it. It made it a lot easier to start a manual transmission on a steep incline.