This was brought up in one of my threads from about 4 weeks ago. Anyways this was super helpful changed all mine this weekend the fluid was clear and looked new in the diffs and transfer case changed it anyways didn't notice any difference. Maybe if it was black and dirty change it but mine were fine wasted money.

 

If the vehicle's fluids looked new when you replaced them, I doubt you would notice any difference. Mine were all old when I did mine, especially the trans fluids.