In recent months I have experienced progressively worsening wobble or oscillation. I have replaced everything from the pitman arm out in the steering system as well as track bar bushing and ball joint and continue to experience the "Shake". Ball joints and steering gear box are next I suppose. Is there something I'm missing because I'm at my wits end with this.

 

I would give the radius arm bushings and sway bar bushings a look at, this was the culprit for my truck to stop the wobbling.

 

Stock sized tires?
The SD's are really sensitive to tire balancing to induce a wobble.
I did a trip across the US with my 17 and had lost a few weights (incorrect attaching clips) and pretty much any bump of size would generate or escalate into a death wobble.
Tires were worn but certainly usable, but a set of new tires and balance,, been fine ever since.

 

Ugh, that "Shake" sounds like a total nightmare, I feel ya! My cousin had somethin' similar happenin' with his truck. Turns out, for him, it wasn't the usual suspects ya mentioned. Have you by any chance checked out this page? Ford Death Wobble Issues Might be somethin' there you haven't thought of yet. Hope ya figure it out soon