I just bought an 84' Holiday Mansion that has an electic head with a macarator on the _base_.  The flush in a switch on the wall above the sink and it also has a guage to show the level of the holding tank.  The level reads about 3/4 full, but unless I'm mistaken, I did not see a tank where I would expect to find one.  It appears as though it was set up to discharge straight out.  I know this can't be used if this is true.  Any chance I'm missing something here?  Why a guage and no tank?  Help!