2001 Disco I started with a small noise with some Pulleys. After investigation, tests, ans I narrowed down to AC bearing. along the way i decided to replace all the darn bearings, Serpentine best, since they are all originals in my truck and it just matter of time. Truck has 90k original miles. I am also doing the VC Gasket right once for all. Last time I screwed up.

Its also due for a fluid changes. here is my plan

Currently what I have:

Rotella 6 with WIX 51515 filter– I am moving towards Rotella Dino (because of constant leak with Synth

I used Mobile synthetic 85/140 gear oil for Both Diff and TRansfer case - i am opted to switching to Walmart Super Tech 85W-140 High Performance Gear Oil (I know it's not made by Walmart). I need about 7 qt to replace all 3 diff and transfer case.

Valvoline MaxLife ATF for transmission – keep the same as I will not be able to flush all out

Valvoline synthetic Dot 3 & 4 – keeping this I don't need to mess around with this one for now

Please tell me if this is not a good idea and why not ?

Thank you for your suggestions in advance. here is a pic