I have a couple of 6pack base plates just found this one I have no clue as to what is from any ideas?

GM 427 Corvette Tri Power base, maybe Not like any Mopar I've seen for any productions cars, 440 or 340
Maybe early 390/406/27 Furd

I’ve never seen a Ford or Chevy base like those. The one with the small notch and the shield looks like a 70 non fresh air. The question is where is the brace on the end carbs for the stud to go through. Maybe they are just not completely finished or mistakes for the supplier.

somebody could have removed the brackets to install aftermarket carbs.

You can see spotweld remnants where they pried the top bridges off.
It appears to be one of the early re-issues from Chrysler in the late eighties into the 90's under the old part number 2946389.
The tooling was modified with that long notch in
the front, presumedly for the AC crowd.
Below is the original Chrylser issue style

Can you take better pictures , all 3 are cutoff only showing sections instead of the entire unit

Looking closer at your pictures I see they are of the two different air cleaners that you have.
Top one is the 2946389 fresh-air style unit and second picture is of 3418717 non fresh-air style with the front shield attached

It looks like no carb braces on either one. Were they cut off at some point or they never had them?

people want mechanical carbs and an easy go to is the 500cfm'ers. the choke towers either have to be removed or the brackets removed to fit the carbs. a mopar air cleaner base won't work with corvette carbs unless the choke towers are removed, or brackets removed. either way somebody was probably playing with non mopar carbs.

The stud brackets were definitely cut off here's some more pictures

all three of the OP's pictures appear to be of the same air cleaner

it has been modified - the carburetor bridges are gone & I believe the air shield has been added

this piece was sold thru Direct Connection/Mopar Performance in the late-'80s/early-'90s with the cutout on the driver's front for A/C compressor clearance

The pictures are so close, they are confusing. I see two air cleaners. One with the air shield and small notch on the pass side and another with no shield and the bigger notch on the dr side for the ac compressor. I’ve never seen one with the ac notch. It’s clear from the bottom picture that the bridges have been removed on the outboard carbs. I bet your right. They were modified for three Corvette carbs of three center Mopar carbs. I’ve used three center carbs at one time before. I did not modify an air cleaner though.