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best thing to do is to go have a look at the wreckers, they always have lots of vt's and vx's to take parts from. you could plug the holes with the rubber inserts as mentioned if you don't mind them. the only problem is that if your spoiler has the brakelight built in and you remove it your car will be unroadworthy as you need three brake lights and if your car gets rear ended your insurance may not cover you.
im pretty sure you could get a brakelight for your rear window from a model like an executive or something but i am unsure of the cost.