Okay, perhaps it is a fours speed with over drive. On those four speed Auto's, I know that there is an over drive relay in the passenger side foot well. Maybe that's what is tripping you up. You may be able to either salvage it by disassembling it and cleaning it up or simply replace it.

Man, if that's all it is that would be awesome. I wonder if a three speed transmission makes any sense on a vehicle like this.

89 Raider - V6, Automatic, rear LSD, A/C Retrofit, Cruise Control Retrofit.