On the HMMWVs all hub reduction boxes, transmission, transfer are vented to the air filter. The "Fording Kit" (standard equipment for the Marines, optional add-on for the Army) I'm not as familar with. Beyond the obvious snorkel & exhaust stack,I know they run a selector valve which control venting to the bottom of the hyrdraboost, and fuel cap. I thought they also vented the fuel feed pump but I'm not sure on that one. I'll have to take a peak when the Jar-Heads down the street return from Legune. /forums/images/graemlins/wink.gif