1997 GMC Safari Owner's Manual - Page 94

REVERSE (R): Use this gear to back up. Don't leave your vehicle when the engine is running unless you have to. If you have left the engine running, thevehicle can move suddenly. You or others could be injured.To be sure your vehicle won't move, even when you're on fairly level ground, always set your parking brake and move the shiftlever to PARK (P). See "Shifting Into PARK (P)" in the Index. If you're pulling a trailer, see "Towing a Trailer'' in the Index. Ensure the shift lever is fully in PARK (P) before starting the engine. Your vehicle hasa brake-transmission shift interlock. You have to fully apply your regular brakes before you can shift from PARK (P) when the ignition key is in the RUN position. If you cannot shift out of PARK (P), ease pressure on the shift lever -- push the shift lever all the way into PARK (P) as you maintain brake application. Then move the shift lever into the gear wish. See you "Shifting Out of PARK (P)" in this section. NOTICE: Shifting to REVERSE (R) whileyour vehicle is moving forward could damage your only after transmission. Shift to REVERSE (R) your vehicle is stopped. To rock your vehicle back and forth to get out of snow, ice orsand without damaging your transmission, see "Stuck: In Sand,Mud, Ice or Snow" in the Index.