TM 9-2320-209-10-1 (2) The M50A1 and M50A2 (fig. 2-8) water tank trucks have an exhaust bypass valve and a bypass fording valve. The exhaust bypass valve is opened to let exhaust gasses heat the water in the tanks. The bypass fording valve is used to close off the heating chamber. under the tanks, while fording. 1. 2. 3. Manifold Exhaust pipe Exhaust bypass valve Bypass fording valve (deep water fording only) Figure 2-8. Exhaust System 4. Muffler 5. Tailpipe Component Location (M50A1 and M50A2 Trucks). 2-10