Darrell used Randall solid state amps, Dean ML guitars, Bill Lawrence pickups to get that sound. While I liked Pantera when they were a club band (mid 80's before CFH and Phil Anselmo back when Darrell was called "Diamond Darrell") his tone is not one of my favorites. I would think one of the harsher metalzone type pedals and a compressor/sustainer pedal would do the trick though any decent pickup will make a similar sound.
Dimebags tone can be easily achieved with a Randall. I had a Randall Cyclone head which I sold just recently, only due to the fact that I had to choose between the Randall or a Marshall (the Marshall was more versatile).
However, the Randall's tone for rhythm was the heaviest I've ever heard, even heavier than my Marshall JCM. It was just a brutal , thick, edgy crunch. It had a monster sound for rhythm, but lacked for solos.
So, find yourself a Randall and you'll be in business. They can be had for relatively cheap on Ebay.