Big advantage - absolutely holds pinion angle - will not allow allow axle to wind-up spring around wheel axis. But does not interfere with leaf springs, lowering blocks, shock mounts etc. To race you need to preload right rear - but to cruise - spring rates are best the same both sides. Put one airlift bag at the right rear to handle racing preload (when required).    

The link had a single heim joint clamped up to a simple bracket adjacent to the tailshaft housing/u-joint. (Looks to me like a big Moog tie rod end would work fine for this application - mounted horizontally into a tapered hole block - and then it would have a grease zerk and threads for length adjustment). The other end appeared to be rigidly bolted to tabs welded onto the rear end housing - bolts looked 1/2" or bigger and seperated vertically by maybe 6 inches or more. Fabbed out of small square tubing for the most part. One observation I could make - looks to me like whatever you build needs a "safety" loop on the front end just like a driveshaft - having a reaction link fall down would have a similar ugly effect.

There were four vehicles with Y-blocks - one was a very nice, hammered 50 Merc with Mercury valve covers. I now know why it is so hard to find decent Y-block T-bird valve covers - the other three engines were in fat fendered Ford trucks and two sported the shiney bird parts. All had four barrel intakes of the Ford variety - 3 Edelbrocks and 1 Holley in the mix (I'm taking a personal survey). If the Y-block would become as popular as a street rod engine as the flattie - we would have nifty hard parts running out our ears..........

That turnbuckle looks like a nice addition (adjusts the pinion nose angle) and so does the shackle up front (adds fore and aft float).