I've never heard of them. Can't find one either. Someone else might chime in with more info, but I've never heard of them being used/needed. The bulbs in eBay kits are all rebased to 893 anyways so it should fit in the socket regardless of whether it has an "adapter" or not.
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2001 Ford Focus SE, Black - R.I.P.
2001 Ford Focus ZTS, Silver - Hella Dual-Projector Headlamps Painted, Morimoto 5000k 35w H9 kit, eBay CAI