I've read a number of links that talk about modifying a strainer basket lid for engine flushing, so I thought I would give it a try. Success.
I modified the lid of a Vetus 330, both my genset and engine use this strainer. I drilled a 15/16" hole and then tapped it with a 3/4" NPT Pipe Nipple. I filed grooves down the length of the threads of the nipple to emulate a tap. $2. The idea was given to me by a gentleman at local home improvement store.
The modified lid works great and I was able to flush the engines last night by myself. The Yanmar 4JH5E took about 3 gallons, and the 7.5KW Onan about 1/2 of that, so 5 gallons could do both. Your mileage may vary. It took me longer to get the lid off of my genset strainer than it did to winterize it. I had to remove the ventilation hose to access it. PITA! I'm moving it to the lazerette next season.
I have a new lid and O-ring on order, part# FTR3301. I don't trust my butchered one as an actual working device now. It will get stored in the parts bin until next year, that is if I'm not in the Caribbean by then, in which case I won't need to use it.