Does anyone know what the threads are for the drains? Seems like if we can match the threads adding a drain/fill system would be easier. I already used a dimple die and turned a chamfer on the inside of the thin nut - no leaks, but i would like to bore out the inside of the drain and hook up a system with a bigger drain = less clogging.
The internal threads the stock plug fits into are 1/4" NPT.
What is the external thread ?