Does anyone know where I can get a new seal for the firewall where the AC lines go into the cab?

Here's a picture of what I'm talking about:

 

I would just RTV it up if it was me.

 

I've got some RTV, but because of the depth of the hole I'd like to get a replacement for the foam. I'm not finding anything on Rock Auto and most junk yard ones are going to be deteriorated, so I'd prefer new.

Anyone have experience replacing it?

 

Gotta pull the dash and AC unit to replace it.
I doubt that gasket is FS anywear.
Might as well use sealing foam from a hardware store.