Weird Stereo stuff
I replaced the stock Clarion stereo with a new Alpine deck, and replaced the stock Philips speakers (dash and rear side panels) with Boston Acoustic. The stereo went in slick as could be - I'd recommend the stereo and buying at Crutchfield because they include DIN pullers and a snap-in harness that connects right up to the stock SAAB connection -0 they also include master sheet instructions for the SAAB, and they helped. I would NOT recommend the Alpine powerpack (KTP-445U) because the wiring is counter-intuitive and confusing, and there's no real good place behind the dash of a 1990 SAAB 900 Convertible to fit the unit.
As to the weird stuff - Philips DOESN'T label their poles on their speakers, so you have to guess which ones are (+) and which ones are (-). The stock speakers do have narrow and wide tabs, so you'd figure there would be consistency there - but such seems to be NOT the case. The narrow tabs on the front speakers were (+) while on the rear, the wide tabs were (+). So I had to shift all the wiring around. No big deal, but it would sure have helped if the damn things had been labeled from the outset.