I've seen another pair in the sn 15xxx range with those polyester film caps. There was at least one dealer I know of (can't recall the name at the moment) that only sold their DQ-10s after changing out the electrolytics at the time with film types and stopped when Dahlquist introduced their factory polyester caps at sn 22000. There were also several outfits selling various film type caps as upgrade kits for the model. These aren't factory caps, so they're likely from one of those two cases.
