Sorry for the delay. Who would have thought that the rear shocks and mounts are the most challenging part of the entire project? But they are.
The shock mount studs were something I already had in my junk collection - er inventory. I probably found them at a swap meet or yard sale.
I just Googled "shock mount stud" and found dozens of results including this:
http://www.ebay.com/itm/UNIVERSAL-SH...-/221463424618
However, as elegant as this solution seems to be, I have since changed it because my shocks were bottoming out too easily. It looked like the studs had bent, but in fact the mounting plates on the axle were deforming. I had to compress the shocks several inches to slip them onto the studs and there was not enough travel left. Shorter shocks would help but that would reduce overall travel, negating one of the advantages of the longer springs.
I tried drilling new mounting holes in the plate, which moved the studs down about an inch and a half, but that was not enough. So I mounted new shock brackets on the trailing arm using the original shock mounting holes. I inserted bolts up from the bottom so they do not protrude downward, as the original Previa shocks did. That cured the bottoming out problem, but now they top out too soon. That is, I have very little axle droop before the shocks reach full extension. Better than bottoming out, but it can't be good for the shocks. I could attach limiting straps like the rock crawlers and desert racers do, but I'd rather just get the shocks right.
By the way, I got those lower brackets at a 4WD shop, but here's a source:
http://www.qa1.net/suspension/street...onversion-kits
So I'm still working on it and will keep you posted. I'll post a picture of the current setup next.