[twindman]

There are many types of slide out seals, so make sure you get the right ones. I went to a Keystone dealer (tho not a Montana dealer) and he had me send him a picture of the seals to order (I was out of town) to make sure he got the right ones.
I think they are around $3 a foot. On my 2980, there was a screw at the bottom and one at the top (a side seal on the slide) to hold it in place. The whole thing slides out when the screws are removed. Oh, and the top screw was actually installed form the INSIDE!! Kind of tricky to get at. I spent about 2 hours working on the one seal, but if I knew the screw was on the inside it would have taken about 30 minutes or less - probably 20 minutes now that I know what I am doing.
I haven't replaced the top seal myself yet - but I have the seals when it goes bad now!!!
Good luck.
p.s. Oh, I forgot about maintenance - I think there is a dry lubricant you can spray on that is recommended (by my dealer).