I heard a beep from the dash, but no warning light or message. Thought it must have been my GPS warning of upcoming traffic since it was getting thick ahead. About a minute later I got a loud "pop" from under the truck (2005 Expedition, 101K miles, 4x4, 5.4L) and it dropped out of OD and the lock-up stopped working. Drove it home like that with no issues, just the higher rpm (3000 @ 50 MPH... 3.31 rear axle). I've searched the forum here read about the OD servo retaining ring popping out and causing OD to go since the band can't be engaged, and about the solenoid failing or the band breaking. No one has mentioned also loosing lock-up on the converter though. So am I looking at a trans rebuild or a simple fix? I tow my camper with the Expy, but this happened while I was just driving around. Towed the camper to the beach, was there six days with a bit of driving around, then this happened the evening before I was ready to go home! Drove fine except for the higher rpm. Towed camper about five miles to a storage facility then drove the Expy home, about 170 miles. Just took it slow and everything was pretty much normal.