I would definitely second Fitz's suggestions about upgrading with later (Alpine) Volvo OEM equipment. Note that the CR-814 will run two dash speakers from the head unit, and four from an external amp--your choice of amps easily available is the 4 x 20, part number 3533004, and the 4 x 40 amp used in the 960, the part number for which I forget. However, any of the earlier volvo amps using the 6-pin round din connector from the prreamp outs on the head unit to the amp con be used! I am presently using an ancient 4 x 20 amp with a CR 814 in one of my vehicles.
If you do not want to use an external amp, but want the single-din size and more than two channels, one of the models to look for is the CR-905, which will run all 6 speakers from the head unit.
if you have access to a u-pick type of junkyard, start collecting wiring harness connections and the round black amp connector cables while looking for radioLook for the amps while you are under the dash at the yard, and grab the amp and entire amp-headunit-vehicle harness with it for just a few bucks
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We have met the enemy and they is us. [Pogo] S70 T5 cop car : Rough Rider suspension, Walmart fog lights, eBay speakers, ambiance by Pall Mall, trim by Le Duc d'Tape, 8-channel THD by OEM amps