it would be great if there is a tool to measure the tightness on the diff.
i found one way to measure it: measure the gap with some calipers that is in the diff clamp. How tighter the diff, how smaller the gap on the clamp.
It's not perfect, but i as a rookie driver i do'nt have the experience to feel if the diff is set right.

But a real tool for it can be made i think. just have something you can attach at the place where the wheels normally go. And than you turn the diff and the device measures the amount op power needed to turn it one full cycle.
Something like that could work i think.

but i also got a question. I recently bought a new set of shocks because of breaking both front shocks. With the old ones i just fill them till the top, screw the lid on and the excessive oil will bleed out. But when i do that with the new ones, they are still too full, i can't compress them.
So then i just filled them halfway but than they are full of air, so how to fill the shocks correctly? The only change with the old shocks is that i now got the red bladders in them.