I noticed a couple of hard shifts on the way to work. When I left work it came out of gear going down the highway. Almost like you just put it in neutral. When I came to a stop I tried to go through the gears and nothing. I turned the engine off and cranked it back and it would go in gear for a 100 ft or so and come back out again. My truck is a 6.0 4x4 with 120,000 miles. I mainly drive to work and pull a cow trailer once a month. Any help is much appreciated.