Standard Back Box for recessed heater?

[Arlen Angell]

I installed a 1500 watt 240Volt electric recessed heater in my bathroom over 20 years ago, and it's in need of replacement. Something that I always wondered way back when I installed it, is if there is any kind of standard to the metal can that they mount in. I'm hoping that I can stick another one in there without busting the whole box out of the wall. I do recall that the back box was marked "AB Back Box" and I wasn't sure if that was any kind of a standard size.