Joe,I would think that the ecu would not let the dd60 turn over2100-2200,but that must not be the case.I did the math and there is no way a coach with a 4.86 gear can run in the triple digits,but the 4.56 can if the dd60 will turn 2300-2400rpm.I am curious,have any on here driven an xl2 with the old suspension verses the new(50,500-54,500 GVWR)?