Just wanted to share my experience fixing the rear window on my 2004 bigfoot
17. The butyl tape was getting very cracked and brittle at the top corners but the big problem was the foam seal that seals the window shut for the emergency escape
was pulled at all 4 corners. So water was easily coming in when it rained.
I unscrewed all the screws from the inside and pulled the inside frame off. Next I used a putty knife to crack the butyl seal on the outside. Spent 2 hours getting all the old glue off the foam tape with alot of elbow grease and mineral spirits.
I found black butyl tape at lordco and the foam I used was from Amazon in 15 foot lengths ( there is actually 2 foam seals I replaced) I knew I wouldn't have been able to properly clean all the old glue to get a good stick with the new foam so I pulled the window.
Amazon link to foam seal was the exact size I needed plus quality 3M peel off backing. 2 - 15 foot lengths for 21 bucks
Black butyl tape is proform brand in also in 15 foot length
Finished it off with RV ezee gutter to keep the water off.