Hello,
Good Question indeed!!!!

I have an original NOS as in "Still in the original box" Mr Norms tri power air cleaner set ups as a spare for my 1971 Demon GSS car.
It was made by Segal and I looked all thru the paperwork and the box and found NO PART NUMBER for the air filter itself !!!!
I bought it off of ebay years ago ( 10 yrs or so ????) and now ONLY use it for when I show my car, and instead use another that I have (pictured both together ) that I use to drive around on and hence keep the original only for shows.
I will post the pictures to show you what I have found in the 34 years I have owned the car...
I, like so many others have been looking and finding nothing.
Segal went out of business a long time ago.
Cal Custom was not the manufacturer !!!!
I cut and used a six pack K&N and just cut a section out of it and reglued it back together using the base plate and lid from one of my norms cars to hold it in shape until the glue dries...
The ford version is not the same and is skinnyier in the middle portion and not at aall the correct shape. ( I know 'cause I tried it once back in 1984 and ended up giving it to a ford guy because it would not fit. The Chevy ones are not a match and are even worse fit.
The motor pictured with the original NOS air cleaner is during a recent rebuild of my 1971's motor and it used chevy carbs and not the mopar carbs as stock "Mr Norms"..
We just rebuilt them and are still using the carbs it was born with..

I will look for more info about it and hope the pictures I included help you.
It was a paper filter element.
I collect Mr Norms cars and have 5 in my collection of 9 mopars that are original from GSD.
I can be reached at 407-947-9005.
Grant Eaton
Eaton Gear/Superchargers/Champion Steel
1155 6th st. Orange City, FL 32763