All of the "SC" units should be interchangeable with regard to being able to plug in without modifying the wiring, except for the SC 901 (which would require an external amp).
The SC 815 had some glitches in the CD function, which were improved in the SC 816. The 815s that were traded in to Volvo were often upgraded with a rebuild to eliminate the glitches, as well.
Use the search function at the bottom right of the page to check prior posts on these units.
The usual radios were indeed gray or black--maybe the seller you contacted had put a fake wood-grain kit on his.
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We have met the enemy and they is us. [Pogo] S70 T5 cop car : Rough Rider tires& suspension, Walmart fog lights, eBay speakers, ambiance by Pall Mall, trim by Le Duc d'Tape, 8-channel THD by OEM amps