All the way to 1991, E-series was Kingpin. 1977-91 was the squared-off look, and Kingpin. Starting 1992, the rounded look began Ball Joint. Your kingpins COULD be worn out at 110,000 but ours were not.
As I mentioned above, I put bushings in ours and I'm sure it helped but was not the Night/Day difference that the Hard-Bushing Sway Bar End Link Kit (from NAPA in my case) and adjusting the toe setting did.
My neighbor did side jobs as a mechanic and brought home an E350 cargo van that was all over the road. Had a set of kingpins to put in it. We inspected carefully and found the Axle-to-Crossmember Bushings were SHOT! No rubber left in them. He returned the Kingpin set and got Axle Bushings. Replaced them and the steering and wandering were all cleaned up. That E350 axle is massive. Hard to knock out of alignment.