Hi Guys.  I'm a new member to the forum, but I've already learned a lot just by reading some of your posts.  I'm looking to change the exhaust manifolds on my 1955 Townsedan from a single exhaust to duels.  My queation is, what letters should I look for in front of the numbers?  A guy at a local swap meet said ones with the letters ECH were right for my application.  Is this true?  Thanks ahead of time!!

Mike