Hi, just to add a couple things I learned towing a 15K lb 5th wheel with my 01 7.3L which is a little different than yours but not much. There are two places on the drivers side of the tranny that will take your sensor. Both will work but I think the lower of the two is better. When towing in summer the tranny temp will be around 190 or so, it can go higher on a hard pull. as I recall the guage pegs at 230 degrees. My rule was at 220 I would pull over and let it cool down, don't shut down the motor just let it idle until the temp gets back to normal. Also, I think the 99s and 00s had inferior tranny coolers which were improved in 01. You should consider an after market cooler. they are not too expensive and will help you a lot. Also, on ebay you will find a number of kits that allow you to lock up the torque converter which will let the tranny run with a lot less heat. They take a little getting used to but will help a lot. Most will also come with a kit to use the exhaust butterfly valve as an exhaust brake which will help going down hills. Those 99 to 02 trucks were great but the tranny was the weak link. Make sure you maintain it and change the fluid as per the book. Hope this is helpful and I reccomend you go over to the 7.3 forum, a lot of great folks on there and they will help you mod the truck and make most any repair. Good luck