The gears are 4.10 Ford Racing. well we installed them. Checked pinion depth, gear pattern, back lash, and turning torque. Everything was to spec. The gear pattern was perfect it was text book. I go to drive the car and it sounds like crap. Its rumbling and roaring so we are going to take it apart agin to see what the problem is. Using Motorcrasft 75w140 syn with 4oz Ford friction modifier. Any suggestions would be great. The backlash was at .010 and the turning torque was set to 16in/lbs.