DML FAQ : Chassis : Can I convert my rear brakes to discs?
It's not worth it unless you upgrade your front discs also. Then you have to mess with a larger master cylinder and balance the bias between the front and the rear. The front 11" rotors are fine, but you would then have to use no larger than 10" rotors in the rear with two piston calipers at the largest.
After going through the install of the Viper rotors/calipers on the DACUDA, I would not recommend it for the faint of heart. Took a long time to get the adapters right and the spindles are now dedicated only to that set of Viper calipers. The rotors are 13 inch diam, which does improve braking distances.
With a stock system and 4 wheel ABS, you will be able to beat this setup though! We did run the tests. DACUDA with Stoptech Viper brake upgrade package, 60-0 mph, 127 ft. 2001 Club cab Dakota with 4 wheel ABS, 128 ft. No real difference.
For the money, get the 4 wheel ABS system. To modify and try to set it up, it is not worth the trouble for the minimal gain you get.