No disc kits but a bunch of guys have engineered discs and even replaced ball bearings with rollers. Do a search on the topic. I paid $50 for this hydrovac off a GMC big bolt. It mounts behind the original master and works extremely well with my stock 12" shoes.
http://picasaweb.google.com/orchidskip/HYDROVAC?authkey=57r0_h37YH0#ABS does not have a kit for a 3600 but they were willing to convert my truck in their shop to front discs and replace all the brake lines plus a dual booster for $2k.
http://www.abspowerbrake.com/catalog.htmlProbably worth it, but...A good compromise would be a dual booster and keep drums. You will be surprised at how well it will stop. No more white knuckle rides and steering wheel bending. Of course those standard brakes are perfect for terrorists since they plan to blow thru the gate without stopping anyway followed immediately by blowing up a perfectly good truck.
