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!

A 1984 boat, by law, must be delivered with either a holding tank or a treatment system if it has a head installed on the boat.  The law went into effect in 1980.  It's possible that some time in the past 20 years, a previous owner removed the holding tank, then re-plumbed the toilet to discharge directly overboard.  But again, it's illegal to pump a toilet directly overboard ANYWHERE in the U.S. 

    I know this post is old but I Thought I might be able to help .. the Head is probly a recurculating Head .. has a lever at the bottom to dump it into the holding tank ( this was a normal install in the year holiday ) when you pulled the lever it dump the waste into a holding tank under the starboard side bed. Sometimes when the tanks go bad people only use the holding cap. of the head and when they are ready to pump out the pull the lever then pump out.. Let me know if you find it ....