[Ron Ramirez]

A = 25 cycle AC (25 Hz) set. This is actually better, as the power transformer is beefier than 60 cycle power transformers (contains more iron) since it is designed for operation on 25 cycle AC. You can run today's 60 cycle (60 Hz) AC safely through a 25 cycle transformer, but you cannot use 25 cycle AC on a 60 cycle transformer.

A 645 console designed to run on 60 cycle AC will use the same cabinet. You could always save the chassis and find a better console (or even a tombstone) cabinet to put it in.

25 cycle chassis are far less common than 60 cycle models.