'Made in Japan' Thomas Question

Thanks DuckGWR for your most comprehensive reply, and the link to the relevant page on your website. Mine does have the sticker but the printing on it is almost illegible. My best guess is B5, which would make it February 1995, just about acceptably squeezing in to the timeline you have laid out, though I wouldn't put any money on it. It might show up a lot better under UV light, but that will have to wait.