Jack, is that a bad thing for a car built to only go straight?
We had a 4 link with a panhard bar, on a very narrow car, the bar was really short and suspension movement up and down also caused right and left rear steer... not a lot, but enough to make the car wander.
We changed that to a 4 link with triangulated top links, that eliminated the movement and made the car more stable but the rough courses of late caused a little bit of body roll and that made the drivers a bit uncomfortable.
Looking at some cars on the salt, I noticed some commonality, a lot of the Special Construction cars basically had a swingarm rear suspension. That pushed me this direction... if it ends up not working, I will rebuild it with something else. I can tell you there is no sideways movement, and no flex in the entire setup. Both wheels will move together, and the coilovers will control that.... with any luck. Hoping it will be a lot like having a solid rear, but with some suspension movement.
Any suspension guru's out there what to chime in?