I think when you find a donor car and remove the headliner (carefully, as you'll likely want it too), you'll find that this won't be a job for a sunroof installer, rather, it'll be a job for a auto body tech. I think the best way to do it would be to cut basically the whole roof off the donor car, and the same section out of your car, and weld the sunroof one onto yours.

If you choose to do this, it would be a good time to rebuild hte whole sunroof system, as they are problematic.

Also keep in mind, wagon setup might be different, so you'd want to find a sedan donor.

Personally, I'd not bother.

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-Matt I ♥ my ♂