I do have a 2 speed rear end 9.00 on the low side and 6.61 on the high side. Have installed a Brown-Lipe, and it helped. Now in overdrive I am turning 25-2700 doing 55 MPH I would like to drop that to around 1500. The 454 pulls good at 2000-2500. I can always down shift it to stay in the power curve.