"I always overfill my diffs, if you run the rear wheels for example, up onto ramps you can add a extra pint or so.
I use 75w-140."

more is good?

 

Yes and no, alittle more is fine, alot more is no good.
I am of the old school where you always keep everything as full as possible.
I keep my rear diff overfull because my rear wheel bearings are lubricated by the gear lube not grease.
But yours are not like that, you have modular hubs.
I am not saying to overfill your diffs, thats just what I do.