I purchased the "Doggie Collar" kit from KermaTDi yesterday.
Unfortunately the seal included in the kit is not the correct seal for the connection, it is way too small.
I went to Gebhardt VW in Boulder, CO and they initially stated that you couldn't get that particular seal unless one buys the complete hose ($120 ish).
I stated that I had bought one in the UK with no problem so Joe, at the parts department, kindly checked his worldwide catalogue and came back with the necessary seal (VW calls it a washer).
It cost $8.93 inc. tax.
Part Number is;
3C0 145 117 F
I have informed KermaTdi of this problem by separate email.
I would like to suggest that owners of PD's periodically check this hose connection for excessive movement and if necessary buy a new replacement seal.
Removal and Installation is very simple, takes a few minutes and only needs some form of pick to remove the old seal from it's seat.
Hope this helps.