I'm trying to find the correct spacer that would have been used on '66 SJ k code. After a little research, I'm finding there were several versions that could have been used for 65-66 hi-pos. Bob Mannel's book on small blocks indicate spacers with engineering numbers C4OE-9A589-A and C4OE-9A589-E could have been used. There is a foot note on the version with engineering number ending (E) denoting this was used when there was a PCV valve. The more common spacer seen for sale is the version with (A) ending engineer number. When I look at the E and A versions side-by-side they are very similar. However, the (E) version is machined flat on top and has no outline around the outer edge for the gasket as the A version does. I understand both will be indistinguishable once installed but I'd like to identify the right part of anyone can help here.
-Matt