saw this as an option on a phs from a 70 gto 455 car. is this differant from dual snorkal ?

All of my 455 cars have had this on the build sheet also. The assembly itself is just the dual snorkel. There may have been a unique filter element, but I seriously doubt it (too much complexity on the assembly line- the plant would have wanted a single filter element for a given air cleaner).

My Dad made a habit of ordering this option on his 60's & early 70's Pontiacs. He believed it was of use considering the dirt & gravel roads he occasionally drove on. Strange though I can't remember him buying new AC HD airfilters. Will have to ask him...

My experience dragging in parts, only the filter itself was HD... believe it had a black foam band around the outside, similiar to GM airfilters on the '78- mid 80's Olds 350 diesel engines.

makes sense, thanks guy's http://forums.performanceyears.com/g...icon_smile.gif

That is correct. The HD air cleaner was the filter which has a foam surrounding the paper element. One was on ebay NOS the other day and it didn't get any bid at $9.99 - probably because the foam surround was rotted. I was going to buy it and try to restore the foam but I just don't have the time.