there are some fibreglass copies on ebay - but some are a shocking fit
there is a guy on here with the black 3dr track car which has a very good carbon fibre version he had made with a company who cannot remembver their name - they fit great and also do fibreglass versions too.
If you going to get one - get one from the above as you will know they fit.
I bought one from ebay for a fair bit of money and the fit was shit so ended up buying a genuine ford identical to the 500 version but without the cutout for 20 quid cheaper than my shite fibreglass copy.