Truck has, to simplify it, towed heavy from east to west coast and back 20 times, and then made the trip about 18 more times w/out a trailer. I'd say I got my money's worth. The 1600 stall speed means that at 1600 RPM its locked up solid. I believe the stocker locks at 2600. My understanding is that the factory convertor can slip as much as 20% due to its design. The replacement convertor will allow about 4% until locked. It will also hold a hill, with a trailer. I can't verify until I get it back and try it out. I don't know alot about transmissions, either. The shop is highly regarded and the owner is a rolled up sleeves kind of guy who will work with you. This is a big investment for a 4 year old truck, but Ford looked at it and wanted to put in a new trans. I intially thought [hoped?] it was the temp sensor, and it was, but it was full of metal. FWIW, Ford and the aftermarket shop said over and over they had never seen one go that far w/out some kind of surgery. And alot of the internals are still o.k. All thats ever been done is fluid and filter changes.