All 722.3, 722.4 and 722.5 transmissions have a safety feature which inhibits a shift into “R” or “P” when the car is moving. At or about 9 mph governor pressure actives a hydraulic piston located in the secondary valve body, this piston blocks the manual valve from moving into the “P” and “R” position. Install a gauge in the governor port, the reading at a stop is “0’. Governor pressure is usually ½ of road speed, round off 9mph to 10mph, if you read more then 5psi the governor is bad or the governor bore is worn(case), if not there’s a problem in the secondary valve body.