Originally Posted by Matthew_Armeni

Thicker center oil will mean the truck will have a tendency to wheelie more. The kit says to build the diffs 100k-100k-50k, F-C-R. If you're driving on looser terrain dropping the diffs will improve handling to a point. If you go too low in the diffs the truck will become "grabby" and diff out in turns, it will feel inconsistent. The lowest I would run the front is 10k, center 15k, rear 7k, but that's the lowest. I prefer thicker diff fluids in all of my race cars so I would never run my MT diffs that light, I'd probably stay above 20-20-20 in every situation.
Another thing to consider is the size/weight of the tires. Bigger heavier tires are going to require heavier fluids to feel the same as lighter tires. The bigger tire usually has more traction, more traction means thicker diffs. There's more rotating mass with the bigger tires so when a tire diffs out and they get going they really spool up - thicker fluid helps keep that under control. Another thing is since thicker fluid means less diff action, there's less heat buildup in the diff. You're diffs will last longer between rebuilds with thicker fluids.

Changing diff oil is a fairly quick and easy adjustment (especially the center) so it's worth trying out to see how the car feels.