I'm gearing to replace our garbage disposer. The previous unit didn't have a p-trap in the line to the drain pipe. The drain pipe has it's own p-trap. The existing unit was installed by the house's PO who's an excellent handyman. If he didn't use a p-trap, it wasn't out of being cheap or lazy. Should I add a p-trap with the new garbage disposer? I haven't missed it in 10 years.

The old disposer does the job but developed a 'cup a week' leak from the bottom plate. I read it's most likely the motor seal. I can't find the Sinkmaster 901 in on-line parts databases and motor seals are NLA for Sinkmasters in general. I tried to wing it but the bolt that goes into the motor from the disposer chamber is corroded. It looks more like a carriage bolt head than a hex after my attempts to disassemble the unit.

Thanks,
Sixto
87 300D