unsilenced air cleaner diameter

Are you talking about the air cleaner that would be on something like a 68-69 340 Barracuda/Dart?

If so, no way could you get 2 side by side. Maybe you could do it with the small diameter early style.

If you see some options here, point out what you want measured and I'm sure we can get the info.

http://www.nicksgarage.com/aircleaner.htm