TM 9-2320-209-20-3-3 b. Replacement (Front, Intermediate, and Rear Tunnels). 1. Place front tunnel (1) as shown and aline mounting holes. Using 7/16-inch wrench, screw in eight screws (2). 2. Place rear tunnel (3) as shown and aline mounting holes. Using 7/16-inch wrench, screw in seven screws (4). 3. Place intermediate tunnel (5) over front tunnel (1) and rear tunnel (3) as shown. Aline mounting holes and using 7/16-inch wrench, screw in 13 screws. GO TO FRAME 2 18-12