Well I lost reverse all of a sudden one night in town. Next day when I headed out of town, found out I had no 3rd or 4th as well. Trans is a DTT that was put in June of 2005. The truck has 172,000, with 77,000 on the transmission. Mainline pressure is 140 at lockup. Reverse port in gear at idle is 160psi. Gov port at 30 mph is 45psi. Pulled the pan off, fluid is clean, and no parts. Not sure what is wrong. Any ideas??? All help is greatly appreciated!!!