No overdrive or reverse, 1994 Jeep Grand Cherokee 4x4

Low and reverse share the same band; so I don't know of a correlation with overdrive and reverse. You could have electrical concerns controlling the operation, but I would say it's more likely a valve body related mechanical concern. Have you attempted to remove the transmission pan and check for debris? Metal on the magnet in the pan? Have you replaced the filter and serviced the fluid? I don't think it will necessarily help, but it's something to try that won't hurt.