2000 XJ8. Hey, does anybody have a source or a part number for the triangular rubber seal/gasket that goes between the door frame and the outside mirror assembly? See photos. Thanks!

 

You might best be served by a salvage yard

 

Looks familiar... that sad rubber triangle.

If you scroll down to the last two pictures, you can see what that triangle looked like on my X-Type:
http://jagrepair.com/images/Electric...al%20Guide.pdf

And you can see, how I fixed my triangle, however mine did not look that bad...

But I can still see hope for your triangle: You could use a 1mm thick rubber sheet and cut it to the triangle size you need and glue your remainder (after you trimmed the damage off a bit) onto the new 1mm triangle with black roof silicone... - that's what I would do...

 

Pete,

Sounds like a great idea to just make a new one. No joy looking for a replacement. Called a couple on line Jag shops and they don't have any and don't know if its even available.

 

Yes. And I strongly assume that rubber is damaged due to heat (sun). My rubber triangle was damaged only where the rubber had contact to the sheet metal of the door - those undamaged surfaces had contact only to plastic, which wasn't getting at hot as the sheet metal.
I bought my 1mm rubber on a roll - from either aliexpress or ebay. Just re-use of the OE part what you can use and glue it with black silicone onto a rubber sheet of your selected thickness - probably 1mm, but it comes in thicker material thickness as well, if you want that.

Btw.: The exterior door handles of my '98 X308 do have rubber between the handles and the sheet metal of the door, but all that rubber had disintegrated. I replaced that all - I just cut out new parts from rubber sheets - I think 2mm sheets.

 

I'd probably just make one too, but if you want to take another shot at finding one, I've had good luck with Jaguar Heaven in California or Noma Auto Parts in Texas. Both are salvage yards.