TRUCK ENGINE SOUNDS FUNNY AFTER LAUNCHING & TOWING

I took my boat to beautiful Lake Mead this weekend. The trip and the lake itself were awesome, BUT, I found that the launch ramp we used at one of the marinas was really flat and therefore, had to damn near sink my truck to load/unload. I'd say the water about a quarter up my FRONT tire. So today, I took my truck for a spin and heard what seemed to be an odd sound coming from the motor. Is it possible that going that deep caused a problem to the motor? The truck is running completely normal, just some new sounds. I assume I'd know if something was really wrong, but wasn't sure. Anyone had problems or know about problems with engine/truck damage from loading too deep?

You are more likely to damage bearings, brakes, etc., long before an engine. 1/4 the way up the tire is nothing, but the rear end was probably submerged. Better check to see how high your rear axle vent goes, and it might be a good idea to change some fluids again depending on how deep you went.

You probably sucked water through the vent in the rear end. If you submerge the rearend, which is hot from towing, it is cooled very quickly by being submerged in the lake. The air inside contracts when it cools, so if the vent is submerged it will suck in water. As long as you haven't driven it too far, change the fluid a couple times and you'll be fine.

Bearings, brakes etc is where I would look.
Even U-joints. Change the lube in the rear axle for sure.
If your front brakes are disc, and the rotors were hot when you backed into the water they very possibly warped, but you should feel the oscillation in the brake pedal if that happened.