TM 9-2320-361-10 2-31. OPERATION OF PIPELINE CONSTRUCTION MAINTENANCE TRUCKS (Contd) c. Rigging A-frame for Rear Operation. (1) To remove tailgate and dropsides, notify your supervisor. (2) Loosen wingnuts (15) to free gin poles (13) from side clamps (14), and place poles (13) on top cab protector (12). (3) Insert trunnion (18) through ring ends (17) of boom chains and yoke ends (16) of gin poles (13). (4) Turn trunnion (18) until it locks into place. 2-151