Jerry,Is there anything you haven’t done? Chris
I haven't tried brain surgery, but I ain't dead yet! Wanna be my first patient? LOL!
Quite often, a transmission jumping out of gear, especially high gear, is caused by sloppy bearings at the input and output shafts, and/or the pocket bearing where the shafts meet. The shafts get to wobbling, and the synchro collar works its way back and slips out of engagement with the input shaft splines. Eventually the splines on the input get worn or chipped, and the problem can only be repaired by replacing the worn parts- - - -usually the synchro sleeve and the input shaft. Loose transmission-to-bellhousing bolts can cause the same problem.