The one with the switch is Version 3. Version 1 had the rattle issues so they redid the cab to have a different back on it. Then they added the switch on the last version. I had version 2 and added my own switch plus a volume control mod. I don't remember the details, it was too long ago and before the whole Blades thing.

I wish I'd never sold that amp. If I remember correctly, I traded it in to help pay for my LP.