These are some speakers I found that match the classic 900 convertible extremely well  Easy to fit - the cover is on poppers and simply prises off      4 screws hold the speaker in - remove and disconnect the old speaker      place the new speaker in and screw the screws back in - place the cover back on and a quick shove with the base of your hand to stick the poppers back together      Will fit the the rear without any additional effort  I'll install them for you if you're local to me .. or fancy the effort of visiting for a coffee to talk classic 900's  Beware I have got a PhD in boring for England on the subject    They will update the sound of even the oldest stereo    Not one complaint about my speaker choices .. (perhaps I know a bit more than I thought) 30 sets sold in total          Peak input power : 250 wattsContinous input power (RMS) : 80wattsSensitivity (1W/1m) : 90dBFrequency response : 45hz - 25khzNominal impedance: 4OhmWoofer magnet 10.97 ozDirectional rotational tweeterMounting depth 62.1mmSpeaker size 17cm (6.5')        Fits all models Convertible (REAR only)  1986 - 1993  best wishes Steve      01582 499777  I can be contacted until 10.00pm most evenings and weekends for support or advice