As to rear sway bars, the V6 uses a 22mm rear sway bar. The GT uses a 24mm sway bar, the Boss 302 uses a 25mm sway bar, and the Boss laguna sega used a 26mm sway bar.
Any will fit, as long as you get the end links with them, as you'll never get V6 rear sway bar end links of a 22mm to fit the others, unless you drill them out (not recommended).
Another possible issue would be how it would handle (V6) with a Boss rear sway bar. Without the Boss rear tires/rims, you might introduce a large amount of oversteer (loose), as you are going to increase the rear roll stiffness of the car if using that rear sway bar and your stock rims/tires. The boss runs a 255 front, and a 285 rear tire/rim setup.
If you're talking about the ones on Ebay for sale, I beat you to the rear sway bar! The front one is up for grabs though (I think).
It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt.