I recently purchased a non running 280SL. Its turned out to be the Coil & Ignition Control Unit were bad. At 1st, only the coil was bad, then after a short test ride, the Ignition Control Unit failed too( luckily just after returning to driveway). I've replaced both parts, after doing a spark test & following tests in the Haynes manual. Voltage at battery while running is at 13 volts. Is there something else probably wrong that I should be checking for, that might burn-up the new Coil & Ignition Control Unit? Or is this just an unusual case? My 280TE still has its original Coil & ICU after 370k miles

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83 280TE- 5 spd, 16.5mm rear sway
85 280SL- 15" Bundts, 5 spd