I had an interesting discovery when I purchased a replacement nose cone off Ebay for my Laurentian to replace the extremely brittle one on my car. The replacement was quite a bit more "substantial" than the one that came off it. Here's a photo of the back side of the original nose:

And here's the back of the replacement:

It is much thicker and has a more "rubbery" feel than my original. My original is almost plastic feeling. Needless to say, if you come across the more substantial one, grab it! I remember my dad's Strato Chief had the "rubbery" one. It took several bumps without cracking.
Todd

-- Edited by 69Laurentian at 18:39, 2008-01-14

Could it be the plasticky one was just dried out ?

Ive come across both types and in every case the thinner style ones are brittle falling apart and the heavier tapered ones are much softer and in better condition. Based on build dates I suspect the heavier version came out late in the production run, both NOS ones Ive bought were also the heavier one.

I recently purchased a heavy version that came off a 69 Catalina that had been sitting in a field for decades with the factory paint burned off by the sun. It was still in great shape with no cracking and I used it to replace a crumbling mess ( thinner version) on my bonnie 4 dr hardtop which has low miles and has spent its entire life stored in a climate controlled garage.