Last week I changed the Oil and the Differential Fluid to Royal Purple from Mobil 1. The truck seems to run a little bit smoother although it might just be in my head. I had it done at the Dealer and they insisted that it needed "no slip fluid" added even though I have a 10 1/2 inch rear end.
I had also ordered an EZ Down for the tailgate and put it on this weekend. It works great and I think that it will be really handy while camping this summer. My daughter thinks it is great when she loads her horse saddle into the box. My sister in law said "It's handier than a pocket in your underwear".
Just thought that I would let everyone know that it was easy to install and works great!!
I didn't get any response from my Water Wetter Post but I put that in the Rad as well just to help when towing this summer.

 

I use Purple Ice for coolant additive. Works great, but you need to change your coolant frequently when you use the stuff(or add every 30kmi)

Mega cab is where they must have been confused on the 9.25" -10.5". Your right, no LSD fluid is needed even with the LSD diffs.

Going from RP to MB1 fluid is like pumping shell 93oct and then pumpin Mobil 93oct. No real diff.

Now the diff. could have been in dirty fluid to clean fluid! Hopefully you went with 75w-140 for towing

 

I changed from Mobil 1 to Royal Purple after reading all of the posative reports about RP on this forum.
I do have the 10.5 inch rear end as I have a Megacab 1500. The manual sait that I didn't require the Limited`Slip Fliud but the dealer insisted that they have had complaints of a grinding noise when turning oif the fluid was no added.