Originally Posted by Chad Smith

Just explain a little more and someone would of helped you. All you need to really worry about is the front diff the majority of people are staying close to stock weight in the rear. (stock is 3k) most are running (5-7k). The front diff changes the handling of the car more.
To break it down a little more. Thicker front fluid makes the truck easier to drive, it takes away the twitchy steering or some of the super fast steering this truck has. Going lighter does the opposite.

It all really depends on your track and your driving style you will have to play with different fluid weights and see what works better for you.

(Someone correct me if I am wrong dont want to tell MSU incorrect info).