I purchased the sendor that Bus Depot sells for the type 1, this will
thread into the WBX block but has a larger hex head size for the wrench..I
believe it's 17mm instead of 13mm.  So I had to dremel the block area where
the drain plug resides, it was just big enough for the sender to fit but no
socket, dremel out some metal from the boss in a cicular fashion and the
socket now fits just right and I have a sender that works.

ps...I always use the copper crush washer AND plumbers tape, it has always
grounded properly.

Jeff Birk
'89 Wolfsburg
'82 MB 240D
'59 Commando Runabout - with tailfins