07 2500 with a goerend built in 2011 with 120,000 miles on it now. Btw I do drive it a little hard. The past 2 weeks it seem like a little slow to Shift Maybe it was just me. I was slowing down at a red light got to 5-8 mph. I think it Went to 1st but I heard something and felt something. Like turns green hit the gas little bit some is not right its slipping. I was on my way home 5 miles from home only had to stop 2 times. Yes it's definitely slipping now. I'm draining it right now has a little color to it does not smell burnt. What do I do I'm guessing this a full rebuild probably? It's slipping in drive,2 and 1. It's not slipping in reverse.