I've finally gotten my spindle situation figured. I've verified that 1996 spindles were 1 year only production started around 6/95. Fortunately I was able source 2 good spindles from 2 different wrecking yards.
Now I'm on to sorting out how I'm going to mount the knuckles. Despite apparently many people doing this swap, finding good clear info on adapting the ball joints is really tough.
Here are the different methods I've found:
1. Per
@Brian1, ream the D35 LBJ hole at 1.5in/ft to fit the D44 ball joint. Then machine a custom camber adjuster to adapt the D44 UBJ to the D35 upper hole
2. From this thread:
Dana 44 Knuckles on Dana 35 TTB - Ream the D35 LBJ to fit the D44 LBJ, then use the D44 camber adjuster and UBJ in the D35 beam, tightening the D35 pinch bolt to take up the difference in diameters between the adjuster and the hole in the beam.
3. Ream the D35 beam for the D44 LBJ, then have a spacer machined to fit in the D44 UBJ hole to allow install of a D35 UBJ. Per my measurements, the D44 UBJ hole measures 1.750", the D35 UBJ measures 1.630". (I've seen a few variations of this method including welding in spacers)
4. There was a thread claiming the the D35 UBJ will mount in the D44 knuckle. So far I cannot find any way this is possible. I've looked at all years of D44 TTB and D35 UBJ specs and cannot find any capability without a spacer.
5. Lastly, there's several methods of adapting D44 spindles to D35 knuckles. At this point, I'm not pursuing any of these methods.
So, I attempted what appeared to be the easiest method, #4, and that didn't work. So, next attempt will be method #2. I'll take good measurements and post what I find as I go.