Help K5 mounting Air inlet

have a set of K5s trying to find a way to mount them my problem is that where the bottom flange is a rubber gasket or something of that sort where can I find something to either plug that up and use one of the side ports for my air supply or some kind of flange I install on the bottom that allows me to use the bottom air supply where it mounts up. help please when I purchased my 2 sets of K3s I did not have this problem they were all ready set up for a 1/2 line. Pictures would be nice if anyone can help out or let me know what I need to buy

Not sure if I understand.
There should be 1/2" NPT threads up inside the flanged base.
Are the threads missing?

No threads in there unless the rubber is coating it should I try and get all the rubber out?

Do you have a picture? There shouldn’t be a bunch of rubber up there.
It should be just like the bottom of your K3 manifold.

Will send a picture Saturday I’m out of town working right now

ok I have a picture how do I post it here

here is a picture of the bottom its a little rusty its been sitting in my shed for months now

I would be trying to dig all that crap out of there.

Will try this weekend hopefully I find some threads in there

Never seen that before. Is that actually rubber in there or a broken off thread from an old inlet fitting?