traction bars?

If you think about it, the adjustable pinion snubber takes the idea of slapper bars and just moves it to a different location. A carefully layed out set of slapper bars could accomplish many of the same goals - a randomly bolted on set intended for a Chevy won't. Chevies have symmetric rear leaf springs with a very flexy front section, while Mopars used a much more complex design (even if it looks deceptively simple). They have very different stiffness front to back, and any traction setup that you use has to work with the stiffness and not against it.

So a set of slapper bars could work OK if you took the time to carefully work out their mounting points. A set of well designed reinforcement bars on the front of the springs like Cal-Tracs can work. The real disaster is if you use the sort of traction bar with a bearing at each end and a bracket welded to the chassis. On a Chevy you can get away with that since the front end of the spring flexes so much, but on a Mopar you end up turning the suspension into a rigid triangle that binds up.