Source for intercooler coolant plug gasket

Hello All, happy Easter. I have a 2003 XKR that is due a coolant R&R. No problem finding a replacement thermostat, but I am striking out on finding the intercooler coolant plug gasket. I have checked with all my sources with no luck. The parts dept of my local Jaguar dealer here in Tucson won’t even bother to return my call. Does anybody know of a source for this gasket?