I am hoping Ted can respond to this.  I was cleaning up some parts and noticed that there are three distinctively different cup washers that retain the intake manifold to the heads.  I notice that one is totally dome shaped while another seems to be of less material, and has a flatter area where the stud goes through the part.  The  third variation is about halfway between the two.  There may be more.  Are any of these significant?  Is there a certain year when they were changed?  Thanks

The intake manifold clamps (aka turtles) went through several variations during the years of production for the Ford Y.  I find no fewer than six different styles not including what was made by the aftermarket.  For the 1963 and 1964 Ford pickups and trucks, they were cast iron.  For the years prior to this for both the cars and trucks, they were stamped steel and depending upon the year, the styles or overall appearance changed.  Here’s the link to an older thread discussing some of those variations.
http://forums.y-blocksforever.com/FindPost150181.aspx 

Lorena, Texas (South of Waco)

Interesting. Although there are many different styles, are they all application-specific as far as fitment is concerned? Which is correct for the ECZ-B intake? Can the stamped steel "turtles" be used with the Mummert aluminum intake? If not, does John include aluminum turtles with the manifold?

The Mummert 4V aluminum manifolds do not require the intake clamps (turtles) as there are no notches or cutouts in the manifold where those turtles would normally hold the manifold in place.  By design, the Mummert 4V manifold uses bolts to hold the manifold in place rather than the original studs and hardware.  On my end, I machine the Mummert manifolds so that there are four slots or notches which allows the use of the original intake manifold studs.  Using those manifold studs helps to keep the intake manifold gasket properly aligned during the intake installation process.  Because I use the studs with the Mummert manifolds, I end up using the factory turtles to help take up some of the extra length afforded by the studs.  Here are some pictures that give a better understanding of this.
 

 

 

Unless you’re worried about being concurs correct for the intake clamp style being used, then if it fits, use it regardless of style.  For the 1957 cars equipped with the ECZ-B intake manifold, the supplied intake clamps (turtles) were stamped steel with a slight flat on their tops.  Here’s a picture of those intake turtles that helped to hold the ECZ-B 4V intake manifolds in place.
 

 

Lorena, Texas (South of Waco)

White grease, alone, not enough to hold the intake gaskets in place during installation of the manifold?