Bill,
I have the latest edition of the SWSC (3rd edition) and no mention of that SN prefix. It's possible the 1999 prefix, the last year of 5906 production used that code. The SWSC list only until 1998 as VHN. I checked the performance Center and none there either. The IDPA PC 5906 start with a DPA prefix.
There is a Lew Horton PC 5906 with Novak rear sights, 3.5" barrel.. bobbed hammer.. that's all. Unless you letter it I can't help you. It is a strange SN. Maybe worth it to you?

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