I was wondering if it is possible to take a ball joint Dana 60 and convert it to a Kingpin Axle? Can you put the Dedenber knuckles and stuff on there?
Reason I ask is I may be able to get a empty HP 60 housing and its BallJoint.

Absolutely. Depending on what you start with, it could end up a fair bit more expensive than buying the parts to put the balljoint axle back together, but you end up with stronger knuckles, better wheel bearings, and less maintainance issues down the road.

I started with a Ford SuperDuty balljoint front 60 to make my rear steer axle--centered up the diff, put Dedenbear C's on it, Dedenbear outers, had custom length axleshafts made, etc., just like building a normal front 60.

Cool, thats what I thought I could do.
I am gonna build this axle slowly so that I can afford all the stuff I want.
It will go under the front of my Duramax

It will go under the front of my Duramax

You'll want to measure twice (or three or four times) on that, then. There's very little room around the oil pan, near the left side framerail, where the diff has to live (can you tell I've been under my Dmax thinking the same thing ;) ?). May end up having to retube the short side of the 60 in order to end up with the diff where it needs to be relative to the frame/pan, or run more lift than I want to run on mine (tow rig).

I am glad you said that because I don't wana go really high. I just wana run 37" BFG's. I still gotta be able to tow my YJ

For what I'm after with the tow rig, 37's is really high. I'd be very content to swap it to 4WD and keep running stock tires (it's a dually) and not screw up my gooseneck ball height or have to go to a big drop hitch for the little trailer.

I figure, much bigger than 235's and I'll be into all kinds of fun with the rear duals, and being that I put 25k+ miles a year on it, a lot of that with a trailer, anything I do to my fuel economy, hurts in a hurry.