Working on a model 53 winch (D5C) and ready to replace the cable with 200’ of new 1/2”. 

The existing cable was the typical nub/ferrule and pocket, however it was then threaded through a passage on the center of the drum, before winding. Is anyone else familiar with this? What I find odd, is that the passage is smaller than the ferrule, which means I can’t use a swaged ferrule and a swaged thimble eyelet at the working end. Wire clips will be a simple solution, just curious about that center passage. 

You need the wedge that holds the cable in

I have the retaining pin which goes near the ferrule. Where is the wedge installed?

You need the proper size swedged ferrule...1.63" diameter/42mm and 2" long/51mm.

Yep, I believe it is the #B4, 1.63x2.00.

Still hoping to get insight on just running the ferrule in the pocket with the retaining cross pin, vs that plus feeding through the cross passage on the drum.

feed the cable through the drum and let the end stick into the square pocket and pour lead around itl

None of the literature I have shows anything about attaching the cable. How close is the fit that is preventing you from threading the B4 ferrule?  Could be you can attache either way although I would tend to go for the original version.