Six Pack outboards question....

[b5blue]

  I'm starting to go through my six pack's outboards and found the metering block's "backing plate" is missing. I can tell this left the sealing effect of the brown gasket weak in the center of the metering block. (I'm only into the front one so far but assume they are missing from both.)
  I found what looks to be a "dead on match" with Holley part # H 186-75 from their 4160 vacuum secondary 4 bbl carb. so on a hunch I've ordered two. Anyone know if I'm right?  I tried crossing numbers application but got nowhere on that. 

[Rolling_Thunder]

purchase here

http://chicagocarburetor.com/item-details.php?item=26970

[b5blue]

Thanks!