Try contacting Litespeed to see if they ever put S/N on the drop out. If they built it, they have records of bikes they've made for other labels. At least that's what they told me a few years ago when I was investigating an unbadged titanium bike for sale. I can't remember the details, but they told me that they never did serial numbers in whatever format I was looking at, but did tell me if they'd made it - even for a different company - they'd have a record.