Isn't the scorpion a two cell light?
If you wanted to go with an 18650, I think you'd need to get a 2x18650 body which would be about twice as long. Maybe 18500's would be a better choice cause that would be about 50% longer.
If you wanted a single cell light, I think you're stuck with a strion setup... And a strion is a rechargeable 1x18650 light out of the box.
Fivemega made some E-Series Strion/Scorpion adapters... and they were different, so I don't think the sockets are the same for the two lamps.
Don't trust me, though, I'm just thinking about what you're really asking and what is important to me in a flashlight... and... where this topic should be going. :candle: