I have a 99' F-250 with the 7.3 and one night it was brought to my attention (via the horn on my truck blowing on it's own at 2am) that I had a water leak in the cab of my truck. Little did I know this was the beginning of many other leaks to follow. So to keep this from being to long here is the list of areas that I had water leaking into my truck and what I done or what it took to fix:

1. Water leaking in around windshield letting water drip on fuse box making the horn blow. (Replaced windshield and installer had to use a heavy amount of sealant around windshield).

2. Seems on top of cab cracking allowing water to seep in and drip out on passenger side grab handle. (Repaired by having spray in bedliner put on roof).

3. Seems on back of the cab below back glass letting water seep in and get into the rocker panel. (Removed the bed off the truck and put roofing caulk in the cab seem/joint).

If you look online you will find where people have reported water leaking around the third brake light and cab vents on the back of the cab. However mine were not leaking, but I went ahead and resealed them while I was repairing the other leaks.