I have an AL5(01 DURAMAX/ALLISON combo). If I drop back to my tow tune I get lockup in 2nd no problem, but my big tune with a hot trans and I don't get lockup until the 3-4 shift(makes for a NASTY 3-4 shift). The whole reason for people wanting these tables is because under big power you don't get lockup without a lockup controller.