[Heathkit] Need info: "Canadian Heathkit SB-600" speaker?

[C E]

Hi:Yesterday, I opened up a box from a past auction that I have won.  Enclosed is a speaker that appears to be an "abbreviated" SB-600 speaker.  It is small that the SB-600 and doesn't make provisions for an HP-23 installation.  The case itself is solid, not perforated.  It also has a cardboard backing at the extreme rear, not open like the SB-600.  I received it from a ham in New Brunswick. This is the second speaker I have seen for sale.  I missed an opportunity to buy its twin several years earlier.  Can anyone shed light on this unit? I can take a picture and post to those interested. Thanks. Cal.