My Death Grip tripod did not have a ball-head, so I got the conversion kit from Little Crow Gunworks.
The kit contains everything to change it over to the ball-head without much fuss. Cost was reasonable, don't remember exactly or I'd post it for you.
The conversion took all of about ten minutes and the end result is exactly what I was after. All high quality components.
Is your BOG Deathgrip™ Tripod in your home somewhere, collecting dust. We know, it doesn't work very well. We came up with an optimal solution to get that tripod back in action and ACTUALLY WORK the way you wish it did when you originally bought it. Pick one up today, you wont regret it.
www.littlecrowgunworks.com
If I was to do it all over again, I'd order the Death Grip Infinity tripod that is available in alloy or carbon fiber and has the ball-head included in the assembly. HTH