Has anyone successfully replace the seals/sliders in the small sliding rear windows on a series 3 hardtop (2 windows either side)?

These are the aluminium frame type with a pull out lock on the inside. Some LWB hardtops have 2 fixed standard windows and 2 sliding, mine has all 4 sliding. The tracks are plastic and the window frame splits into 2 and comes out like that. Any ideas? I can post a pic if that helps. I'm not sure if they are a standard land rover fitting or not.