I've driven across the Frio on our lease until the water was running in the doors and across the floor. I did it several times a weekend for the first several weeks after the heavy rains last September. I had no issues related to air intake, but that was about as deep as I wanted to go in slow moving water without a load of corn in the back. The bigger issue is the belt drive and the water causing it to wear faster. When I got the 100 hour service done, the belt had more wear on it than normal and they asked if we'd been running through deep water a lot.