When did Denny's first come to Billings, Montana?

Hi, I'm nostalgic from the 50's to now. i'm just a young adult and I've been trying to figure this out. I'm fascinated by dates and most people say the Denny's didn't come downtown Billings till 1995 and the one on Overland was in 1996. I thought it took too long to get a major sit down chain bigger than Perkins. Olive Garden and Red Lobster was late in 1993. So I heard by a couple people, one guy I emailed at the Denny's corp. said actually those two Denny's in Billings opened originally early in 1993, than AGAIN in 1995 and 1996, the dates I provided earlier the furthest dates back most people have. But there was that record of them being open before, opening early in 1993. I even saw websites and talked to the manager there at the Overland location saying it was like 1985 for that location, Can any of you straighten it out and tell me if it either in fact did operate before 1995? Thanks alot. Shane Keister.