If your turning 1000 rpm's at 55 mph it sounds like you have OD and TCC apply working [...] unit has 2 shift solenoids in 1st both on,in 2nd only b or 2-3 sol. on,in 3rd both off,in 4th (od) only A or 1-2 is on. Some tech info labels the solenoids 1-2 and 2-3 ... Login to read more.