I found that the GTR subframe sits approximately 2 inches lower in the car than the GTT sub frame. So what I did was box the end of the sub frame mounts adding that additional 2 inches and contouring it to the frame of the GTT. Then I drilled 1 inch holes through the existing frame rails vertically and sleeved them with a .060 wall tube. I attached the sub frame to the existing frame rails using 1/2 inch grade 8 hardware. Keep in mind that you also need to modify the driver side floor pan as well as the driver side frame rail to except the GTR transmission mount.