truggy diffs into Revo, what fluid weight?

[_paralyzed_]

Nope, the Rc-M revo adapter has an 8mm bore for 8mm pinion shafts.

What you would do if you want to use a revo shaft is simply get a set screw to use instead of the pin, or dremel the pin portion off.

But, if you are fabbing in a center diff dog bones and cups are the way to go. There are so many shafts available, you should be able to find a combination that works.