Pulling Axle Shafts. Do I Have To Drain Gear Oil?

So I pulled the axle shafts out last night, and like you all said, no oil leaked out.

I did notice what appears to be the thrust plug still in the center of the carrier (489 case, 2.76 gear, open diff). Should I be able to see through the carrier if there's no thrust plug installed?

Does this plug have to be removed if using the green bearings?

I'm removing a pair of the Mopar Performance green bearings that failed after 18 years. I'm now installing the Dr.Diff new style green MO-400 bearings.

I do vaguely remember there being some preload on one side retaining plate, and there was some force required to make the plate seat when I last installed the axle shafts with the green bearings.

If the plug has to come out, what's the best way without having the plug drop in the housing?