I can't provide any input on those particular speakers, but I have always gotten good feedback from Celestion's tech help with any of my questions about new and old Celestion speakers. You can try reaching out to them using the form at the bottom of this page.
Thanks for your replies. Indeed I love the sound. And the cab I purchased new back in the 80's, is still in top condition. No problems what so ever in all those years of heavy duty. So yes, I'm a big fan.
But my question was because I can't find anything about them on the web. I guess not much bass players use them.