Are you sure the transmission is slipping? Does the engine suddenly rev up without an increase in speed? when you accelerate quickly when driving straight, it doesn't slip? There are some bands in the 42RE transmission which needs some adjustment once in a while. So maybe this with some new fluid and filter could do the trick. There could be something more seriously going on as well.
Yes I am sure it slips,but only when I turn left real sharp and quick. I tdoes not slip any other time.I have the trans serviced every 30,000 miles.Thanks for your replies.