can anyone tell me if the rear side pannels which have removable oblong plastic fillers are for small speakers? and did jaguar make speakers to fit?

 

They are probably there to cover the speaker holes if your car doesn't have the rear speakers. Take one off and look to see if there are any wires there somewhere, bound up out of the way. The looms had the wiring, but what speakers were installed in the car depended on the standard of the radio/tape unit chosen by the first owner.