there are a few ways to go about it, really. 2 ways are a triangulated 4 link (the other way in the image), and the afore mentioned panhard bar (mostly used on hot rods and trucks). you would use a spherical bearing, or large rubber bushing in real life at the ends of the panhard bar or triangulated 4 link bars. Nascar uses panhard bars. usually a panhard bar would be used on a suspension with longer radius arms (4 link bars) and the type you are building would usually have some sort of triangulation, but some setups with shorter radius arms do use panhard bars. you can actually connect the panhard bar to the diff housing, or anywhere on the frame, so long as the suspension travel doesn't cause the panhard bar to swing the rear end to one side under heavy load, or when the suspension becomes decompressed.
google image "four link rear suspension" and I'm sure you will find a host of reference pics to find the set up that is right for your application.