[Sirrotica]

It's been hashed over a few times on this forum, and right around 71-72 is as near as I've seen documented of when Pontiac made the switch back to steel upper gears.

[Ben M.]

Originally Posted by Sirrotica

It's been hashed over a few times on this forum, and right around 71-72 is as near as I've seen documented of when Pontiac made the switch back to steel upper gears.

Yup. I've taken apart a half dozen '72 and later 400-455 engines that were factory unopened and none of them have a nylon timing chain. I know they were using them through 1970 at least (Pontiac's 1970 factory literature shows one on the cover), the changeover was likely the '71 model year sometime.