JBL SOVEREIGNS I

I have a pair of JBL Sovereign 1 type C 60. I've had them stored since my day passed away and want to sell them. I would like to know what there worth. I have seen prices all over the map. They are in great shape for there age with only  a small water mark on the top of 1 cabinet. 2 of the clips holding the covers on are missing. I have been asked if they are S7R or S8R . I do not know.  It appears they have to be removed from the rear of the cabinet and  I do not know how to remove the back panel to find out. Any help will be appreciated. 
Thanks