Changing them out is pretty easy..Mine were pretty messed up with the outer rubber missing some pieces from sitting for a lot of years and leaking water down into the door cavity. I asked some questions here at one time and didn't get much for answers about how they locked into place,etc..etc...except by Astrowill who gave me a link to which ones to get that would work for the Astro and Safaris.Mine are 1990 and 2004..seem to have the same length needed for both models(I did the 1990).I can only assume the door flange they hang on is similar.I'll see if I can find the link and edit in here.
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Notice the ends on these ..they are made specifically for the driver's and/or passenger side doors(comes as the set of two).Only the little bit at the square end which fits against the back trim needs to be trimmed.
I did the process with the windows up.Just careful not to put pressure or pound on the glass..besides you can clean the glass that way and check it for a snug fit.
I found the easiest way is to start at the back end of the door and pry(small screwdriver over the back of my hand)/bend UP(the rest of the way with my hands) the outer rubber coated /metal flange that rests downward outside the door pretty much straight out..starting at the door jamb edge above the lock and continue that bend process to the other end..Underneath you will find some small 1/4" wide metal flanges that can be bent out to remove the felt easily from the door's metal strip they hang on.The front end of the felt is under the vertical metal piece so you need to start at the rear and work it up and off the door's metal edge and pull up and out towards the door's rear jamb edge.
Once out clean the glass down to the bottom metal strip it lies in and the area around the "repair".
The new piece will need to be trimmed probably less than 1/8" or so at the opening door's edge to fit snug back in place.Slip it in the front end as it came out,and place it near where it needs to go to see how much trimming is needed to match the outer vertical piece.Then slide it down in place with the rubber tight to the glass and the clips where they should be.I used a 1/2" wood dowel and a small hammer to tap/finish lightly setting the felt in place.Worked grat on the driver's side!
Only problem I ran into was on the passenger side because the back end didn't seem to want to grab.and seal down in place.I pulled it back out and noticed that the strip seemed to be bent with a bow downward in the middle about 3/8"..came that way.I hadn't checked the driver side one.Double check them for that when you get them. I ended up having to add some 3m weather strip adhesive and temporarily taping the back 3" or so down in place,If it doesn't sit down right,it leaves a small gap by the window.
If your felts are bad,cracked,and leaking..replace them.It's a simple job anybody can do.Be sure to run a small scredriver at the bottom of the door and clean out the small drainholes along the bottom seam to make sure all the water that has leaked in can get out..at both ends of the door.