[twindman]

I have replaced some of my slide 'wipers' / seals on 2 different Montanas. The key is to buy the right size width. My memory is a little sketchy on some of them, but on the verticle wiper on the front side of a slide, here is the scoop. These are really just slid into a slot along the edge of the slide opening. At the top in a rather hidden/obscure place was a screw through the mounting slot into the rubber wiper and thru to the other side a little ways. So if you can find this screw, it is a 1) remove screw, 2) slide the seal down and off. 3) insert new one and 4) put screw back in.
Oh, one more thing - this screw is on the inside so you have to search up on top of the slide area a bit. I think if you tug on the wiper/seal from the outside, you can see it slide a little bit.
Now, what I am talking about is the seal that is about 4 inches wide and flops in or out depending on whether you have the slide in or out. These also run across the tops of slides.
One other thing, my newer unit seems to have 2 seals on the top at least. One kind of on the outside and one on the inside. Not sure how this figures into things??
Good luck. Oh, I think the seal is like $1 to $2 a foot. When I bought mine, they had a long roll and just measured off and cut it.