Diesel with 280K miles transmission has worked well to date. While pulling out on road with thick layer of wet leaves, rear tires spun up and then regained traction on dry pavement within 3-4 seconds. Almost immediately, transmission began shifting eratically. When excelerating, transmission shifts to second gear and then almost immediately shifts to third and fourth gears in rapid succession. All shifts are hard thumps. Otherwise drives smoothly once in high gear. Is differential sensor related to shift performance? How to return to normal shifting?

 

Problem solved! Split in vacuum line next to serpentine belt tensioner. Rear wheel slippage appeared to be coincidence.