I did a search and didn't find an answer...

Went to top off the front diff today, noticed what was in there appeared to be water contaminated (light tan milky looking). Only 12k miles on the truck and never been off-road. I see my front diff vent cap is poking out from behind the fender liner where maybe it can get flooded with water. Can the cap really ingest that much water?

that is typical of the fluid condition. Every single one I have drained looked the same with lower mileage even. Best bet is to drain and fill with new

Yep, I immediately drained and refilled with 75W90 Mobil1. Thanks for the info, at least I know I'm not flooding the diff. Still gonna relocate the vent cap to a protected area.

That tan/milky looking appearance is from the yellow gear marking compound that gets left in the front diff to mix with the gear oil. No worries.