I got some generic rails that you had to rivet the fitting to on the end on Ebay, but I don't see them available anymore, this was a few years ago. I have not tried to replace just the felt, you would certainly want to do it right if it didn't stay put it would undoubtedly bind up and mess things up but good. I would recommend replacing or refurbishing if they look to be ratted out, rattly windows are no fun and make the car sound like a bucket of bolts when you go over a bump.