I'm really digging this Peerless IRS.......
this looks pretty easy to build.
I have a couple of those diffs laying around here too......
I think I'd do it a little different though.
This setup is like the old VW bug swing axles......
the camber changes as the suspension cycles.
I'd stack A-arms on both sides, use heim joints at all three ends of each,
connect them to a heavy duty uprights, and add two more U-joints.
Add a sway bar and some adjustable shocks and I think it would ride pretty nice.
If you ever want to sell that thing, let me know.