The guy used the collar-like Proto with a puller that hooked the outside edges. If he'd had the bolts it was set up to take, I think it would have had a better chance. As it was, those two bolts that pulled it together were bowing dangerously. I saw that tool in a Proto set online selling for $645. I'm glad we called it before something gave out.
After lunch today, I couldn't grip anything after all the banging on the chisel.
The heart of the original construction of the dummy diff was my makeshift slide hammer. It was a leftover 2X4 stake pocket from a trailer I'd built, and part of the handle off an ancient lawn roller. The bar from the handle offered a place to hit with a two pound hammer and the rectangular tube just spanned two of the studs on the axle flanges.
Since that span was the same as the holes in the drive shaft flanges, I thought I could use it again for the dummy diff. As it turned out, by welding a 2X2 tube to the other end, the span was perfect. I added four washers to each of the bolts between the two tubes and the drive shaft end flanges to protect the protruding CV joint covers. I slipped a 1.5 inch square tube inside the 2X4 tube to catch a bolt from right rear shock mount bracket to support the rear side of the crazy lash-up. I used one of the shock mount bolts, double nutted to the front bracket to provide the main support angle iron scrap.
Pics of the dummy diff (in the order they posted):
Whole thing from the rear.
Right side from the rear.
Right side from the front.
Left side from the front.