Overfill=More FROTHING=BLOWN SEALS! Just keep that fluid below the finger 1st joint (1") minus 5/8" to check.
DO NOT OVERFILL!!!!!!!!!!!!!

 

I fill mine until it runs out, I have owned countless GM's and have always done it that way as does every mechanic that I know.

 

Thanks for the confirmation Calif Phil!

 

Just a though, maybe other GM vehicles like the Suburban, Yukon, Tahoe, Escalade, Silverado etc (guessing) have similar diffs?

What methods do they recommend for these?

From YT it always seems to be the "till the oil pours out" technique...

 

All the same, just keep the fluid below the fill! When overfilled, wait for overflow to drain out completely before installing the plug.

 

Great images!