Rig is a '93 Rockwood, Spartan Chassis. Cummins 230 with an Allison 6 speed transmission. Halfway through a 12,000 mile trip this past summer, the transmission stopped shifting into 6th gear. Switching to "mode" allowed it to do so. Downshifting, especially in the lower gears, is very sudden and hard. This was all preceded by dropping out of cruise control with no warning, which may or may not be related. This was a one owner coach and the previous owner said he had some problems with the control unit. Possibly heat is the culprit as 100 degree temperatures lasted for long periods of time. On one occasion, when stopping at a rest stop, we stopped and the tranmission was put in neutral, and the engine left running while we cooled down. When pressing the button for forward, the transmission woujld not engage, until we turned the rig off and on again. My question: approximately how much will this require to repair? Are reconditioned units available?