Altec studio monitors

I have traded for some altec 9846-8a speakers, can some one tell me about how old these are and what they might be worth. The story goes they came from an old rca recording studio but everything has a story.

I listened to some of the voice of the theater speakers but I liked these better.

The bass speaker has been replaced with I think a 15" cerwin vega. The bass isnt what Im use to. can I change the bass speaker of better quality. if these are very high sensitivity is the changing of this speaker very critical.

Hey if nothing else they are grey and black they look cool in my black listening room and they are cool at pool for parties.