[Conquistador]

I'm not aware of any sunshades from other models that could be applied, unless you're referring to one of those awful opaque strips applied to the outside of the windscreen.

Most windscreens I've seen on D2/D3s just have a tinted strip over the top 6 inches of the glass which helps reduce glare from a low sun, but it's the glass which is tinted rather than anything applied to the glass afterwards.

(My old D2 and D3 here, both with IR-reflective and heated windscreens, and you can see the tinted strip at the top of each).

That little flap behind the mirror is quite useful, and the main sun shades which pull down for each front occupant also slide out further which is useful for sun coming through the side window -- learnt that from watching a VW Phaeton review video.