Hmmm...trailers in the 50's & earlier didn't have
holding tanks, they were called "park models". They were either plumbed directly into a RV park system or "golpher-holes" were used. I suppose you could remove your tank and plumb directly into the septic tank with your '86 but I am pretty certain this would adversely effect your resale value. We just went to great lengths & $1500 to ADD tanks to our '56 trailer that didn't have them. Without tanks, it would limit the travel-ability of the trailer for you (or a future owner) at a later date.