I installed a pistol grip Quarter stick in a GN a couple days ago. It's supposed to fit 200R4 , 4l60e , 4l80e etc. This was on a 4l80. The shifter arm that goes on the transmission is not even close to being useable. I had to weld a piece on it and redrill the hole.
Chris i milled out and did some welding on a Stage II cover so i could use the stock sensor and bracket. I'll try to remember to get some pictures tomorrow.