TM 9-2320-209-10-1 b. Rigging the Tailgate. (1) Rigging to swing open at bottom for dumping and spreading operations. 1. Pass free end of chains (1) through retainers (2) and through holes at top of locking slots (3). 2. Leave enough slack in chains (1) to let tailgate (4) swing open. Opening must be wide enough for material to slip through when body is lifted. 3. Lock chains (1) in place by slipping them down to bottom of locking slots ( 3). 4-236