I need to replace the insulation strip between the top and bottom parts of my 1998 Towlite 21'. Does anyone know where this weather stripping product can be purchased and if it's reasonably easy to install? Thanks!

Are you referring to the black strip known as P bulb seal? This can be purchased from J&R in Ohio. If this what you need I can refer you to the post that describes installation. It will take you about 8hrs. to install.

I bought 10 feet of bulb seal but there are no instructions on how to install it. Any advice? thank you

See post of 4-3-2010 Outline for replacing the roof gasket by Sam Shields. The bottom part of the post is titled installing new gasket. Have fun.