Two things need to do?

First one ..My rear brakes would lock up….especially after going thru water…I live on a coffee farm with dirt roads, and it rains a lot….& after any car wash…do not just leave parking …take it for a spin to remove any moisture to the brakes… number 1 reason brakes lock up…google why rear brakes lock up….and mines would lock while driving…..dealer remove the rust …brakes seems to be fine for now…that what they told me was the reason..

2nd thing you may want to do? If driving thru water or mud, maybe wet roads too…
My rear air vent diff let water into my 3rd member…the rear diff air vent is suppose to be a one way valve? But mud, dirt, water can get in…mines did…. Cost to replace the 3rd member ? Dealer quote me $3,300.00. , but they said cost of parts went up…my payment was $4,100.
Just got the truck back yesterday..
YOU MAY WANT TO ADD a extension rear air diff venting? I went with ARB venting kit…cost $78.00 including shipping to Hawaii.. I will get it install in the rear driver side taillight housing..see R4T - installation video…

The mechanic look under my truck to explain how it could happens ..sometimes mud gets in and the vent gets struck open… Yep I crawl under and the whole undercarriage is still cover with dried mud…

Off course I am just suggesting the above …the cost to drive around after the car wash..small..the cost of venting the rear diff..small ..there are many cheaper mod diff ..solutions…

 

TLDR:

• Don't leave your parking brake on after washing the truck or driving around through the water.
• Drive the truck after washing it to dry off the drum brakes, otherwise, they can lock up the rear axle.
• The rear Diff breather let water into the axle. The replacement cost was $4100.
• Do not rely on the OEM breather, and do the Diff breather extension mod.