[ QUOTE ]
...That low rise OE Air Cleaner,part #6423907,was used on virtually all chevy big blocks from 1966-1969,including the 69 Z/28 w/2nd hood design.In 1970,they changed to the new OE design,part #6485257,to sit higher off the new low rise intake manifold.
[/ QUOTE ]
So Rick,
The pre-1970 open element bases were lower ( due to increased
intake height ) and the 1970+ were higher ( due to reduced
intake height ). Does that about cover it?
BTW, what the he-double-toothpicks is a 2nd design Z/28
hood? You're not referring to the ZL/2 hood are you?
Steve