How often should the fluid be changed in the rear end

 

Whenever it gets dirty. Really kinda depends on your driving/hauling use.
Checking the level should be an every other oil change kind of thing.

 

Depends on usage and brand/type of gear oil to be honest. If you are doing stuff in water and mud, definitely no more than 30k.

Normal truck usage, which includes hauling and towing or hard driving, about 30-50k.

Some brands such as Amsoil, you could possibly pull off 100k depending on usage.

Honestly, I don't think 100k is a big deal with pretty much any synthetic seeing how most of our trucks never had the gear oil changed ever and made it to 150-200k miles prior to our ownership and the rear is still in good condition with the conventional gear oil that came in it from the factory.

 

Since its such an easy job I service the rear diff every 25k miles.

 

On mine, the PO drilled and tapped a drain plug into the bottom.

 

Maintenance schedule says every 100,000 miles, or whenever it has been submerged in water.
http://www.supermotors.net/clubs/sup...media/833143_1

 

If the rear has clutch type limited slip I'd say 30k, an open diff I'd do it every 50k. Most clutch type diff are not still grabbing by 100k because of poor maintenance. When you can really find some info that digs into if the diff is LS, the mileage for a change drops to 30k. It really does also depend on how the truck is used as previously stated.