We have 2 General Radio 5 amp variacs. Nice working condition, knob has smooth operation.
One uses a 3 prong plug with grounded receptacle. The second one uses a 2 prong plug and 2 prong receptacle. The second one needs a new cord and plug.
We often see these on eBay for well over $100.
The 3 prong unit $55 – 2 prong unit $45.