Does anyone have an idea what boombox model to which this speaker might have belonged?

no idea & if you need them get them... me I dont need them ,,, I have plenty of speakers an such here allready

Come on DM4U.Are you really trying to tell me you don't have the complete 3 piece box that share this same type of speaker?LOOK HARDER!There's one in your house somewhere.It's just a matter of finding it.

bass boost on bottem should make it a little easier.

I would guess either a late late 90's Sharp or Magnavox.

i was gonna guess a sanyo or magnavox/philips. def 90's.

yeah, I'm with Larry King, mag/philips.