36 tooth freewheel sprocket double threaded hub???

yes it does I had one of those back in the day and you can get it cheaper from boys go fast on eBay however the reason why its double threaded is one side is for like a 567 speed cog free to relearn for paddling the other side is for the motor free will which means you will need a pull starter and a wide crank total set up used to have one their ok. So DJ it when you get on the gas the polls like normal but then when you let off the gas your coasting and your engine will drop to an idol.

You can also get hubs and adaptors like these from Staton Inc.

(All humor aside) I have one of those hubs which I purchased on a free shipping deal out of China. The quality seems to be reasonable and I'm going to be using it to rebuild one of the rear wheels on my Hercules tricycle.
A good many sprockets, freewheel adaptors and freewheels are available on Alibaba and most of them are intended for electric tricycles and seem to be reasonably heavy duty.