There were 3 air cleaners used on the 1970 LS6 engines..

1) single snorkle CI air cleaner used only when CI was ordered

2) 14"x3" open element air cleaner used throughout production when CI wasn't ordered

3) "dual snorkle" air cleaner used when CI wasn't ordered..There are some that say this was a "mid run" air cleaner used when complaints arose about noise..I tend to think it was more of a possible supply issue and hence the 14"x3" open elements were used. I have seen a Baltimore buildsheet from Dec '69 with the code for this air cleaner so hard to say "mid run" They are certainly rarer than the open elements..

There was never a "single snorkle" air cleaner used without CI.

Hope this helps