rear sway bar?

I don't know if this helps but I have the factory front and rear setups in my 69.
The front I scavenged out of a 4 door at the yard many years ago and the rear was out of a 75/76 Valiant police package car that a friend had found back when these were around and used on a few of his cars. He traded me for a third member years ago and I finally had installed quite a few years later.
There weren't many of them ever built but they mount like any other b body police package car and it drives very different then it did before hand, tight, both ends kinda move together, and it has a bit more over steer but it corners great as long as you know what your doing. A sure grip probably doesn't help but it keeps things interesting.
If you do find one somehow the frame mounts are a bit wider then the later mounts were, I only had one original mount, and one from a B body and the later one was too narrow and wouldn't go over the rails on the rear of the 69.
We got one out of a diplomat and rebent and reworked it and it seems to be fine.
The car is pretty balanced, rides about the same as before, though it had 340 suspension and a fast ratio box factory, just no bars. I also put poly bushings in it and replaced most of the suspension parts. The book performance handling for classic Mopars can be a big help deciding what package is best for the way you intend to use your car, especially when you'll most likely be using a after market setup.