The Beta Lead 4X10 combo that I have is a self contained head (with speaker jacks, etc.) mounted in a slot in the speaker box. It's not hard wired in any way, you have to plug in the speaker even when using the speakers
in the combo. It looks a little funny because the factory didn't paint the center of the chassis box, but you can just remove the mounting bolts, slide it out, put it on a different cabinet and use it like any other head.
You can see in the picture the marks in the tolex where the previous owner slid the head in and out, and the speaker jacks both in the amp and the cabinet.