I just picked up a complete gasket kit for everything on my car from Detroit Muscle Technologies.
The insulation pad that the non A/C heater box sits up against is a A/C hole type.
i.e: The bigger hole like the A/C motor mounts to.
DMT said they are trying to get that right from their vendor they buy it from.
Right now they don't offer the correct non A/C heater box insulation pad.
Has anyone found a vendor that makes the right insulation pad for a non A/C optioned E body?
Anyway, just let everyone know about this issue also.