I can't help you with the dash number, but in my opinion, ANY pre-lock 686 snubbie in good condition and priced right would have made me stand there unil somebody came over.
I know a thing or two about bad gun shops as I'm surrounded by them, so here's my tip.
1. Call them on your cell phone from inside the store.
2. Tell them over the phone that you saw the gun earlier and want to know if its still there.
3. When the guy comes wandering over to look in the case, introduce yourself, hang up and commence the deal.