CV 746 C PCV valve differences

[Ls6 Ragtop]

Does anybody know when the transition from the heavy steel to the stamped steel on these pcv valves took place? I have multiple different styles of these and thought I had a reasonably good idea of what was correct until I came across a style I didn't know existed.

I was under the impression that the heavy steel without the raised upper half was correct for 69 vehicles and that the stamped steel (dyed purple) ones were 70-up until I received this last one. I got it from a guy who had a 69 Corvette L88 car that took delivery on it in March of 69. He upon delivery transformed it into a drag car ( what he ordered it for ) and the emissions stuff was all removed day 1.

This valve which was with a bunch of parts he removed from the car seems to be a combination of sorts of both styles. It has the remnants of the purple dye on the bottom, (unfortunately a buddy started cleaning it before I saw it and stopped him) and although a different style from the earlier heavy machined pcv's I have it still has a thicker and heavier top than the later stamped steel ones I have with a slightly different profile.

I know when I showed a 69 Z28 at MCACN the gentleman judging felt the silver colored machined one was correct for it (also a March of 69 built car) but now I wonder if that's not necessarily true? Anybody have any thoughts?



The pcv in the center is the style I'm questioning for 69, it has some purple dye still on the bottom that I would think it was completely covered with like the 70-up style to it's left. The machined style to the right is in a box dated July of 68 and my earliest dated box for the stamped style is 71.
Thanks, Chris