TruFlex is the best way to go. It is semi-flexible, and makes it much easier to "fit" to the body lines with little or no grinding/filling. A solid 'glass cover is just that...solid. They NEVER fit right out of the box....they require quite a bit of finessing(grinding/filling), usually on both the cover and the body to make them fit nice.
Also, the Truflex stuff will "give" a little if someone accidentally gives it a little love tap, whereas the fiberglass one will not...they usually crack. The Truflex stuff will still need a flex agent added to the paint to keep the paint from cracking....even if they tell you it doesn't.
The original style urethane bumper covers are still available, but super expensive.
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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"