Chuck - This weekend was "Street Rodder Days" in Tucson and way over a hundred cars showed up. I found an example with the simple reaction link I described before - but the camera first said "card full" and then "battery low" (the deadly duo). My wife also took exception to me crawling along looking under all of the toys. Such is life.
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..........
Steve Metzger Tucson, Arizona