Timing chain and gears...
 

I would suggest a good quality double roller setup...last time I needed these parts I got them from Eric Jackson. {Vintage Muscle Car Parts}...he has quality parts. Give him a call and he can get you the right stuff!

http://www.vintagemusclecarparts.com/#

X2 Tom

I thought GM used the nylon tooth timing gear to help the Survivor Police tell whether a motor had ever been apart. They knew that no one would ever put one back in ;)

Actually wasn't it for noise reduction? I would think a sproket made of alloy and nylon would be more costly then a steel gear. Don't get me wrong.I don't think it was a great idea.