I just went to B&D racing to find out how much it would cost to get 4.10s and t-lok installed. Does $900 sound too high for gears, t-lok, install kit, install and the comp to fix the speedo. I know that i should get 4.10s because i have an auto but would it be better to get an auburn diff or the fms. Would the auburn diff void my warrenty? What do i need to recalibrate the speedo and where can i get it?