My reading of the Standard Catalog of Smith Wesson (3rd edition) page 401 puts your firearm as made in 1988. The first year that the model 4506/4506-1 was made. They were in production from 1988 through 1999 though some limited custom models were later produced for LAPD. Traditional double action, 5" barrel, 8-shot magazine, .304" smooth trigger, ambidextrous safety. 41 ounces. They are nice handguns, but not rare. The price varies widely with condition and these have generally been eclipsed in desirability by the newer M&P models. Anecdotally, I like mine not only because it is a better 45 ACP handgun than the venerable 1911, but it is one of the few handguns that is heavy enough to use as a club if you run out of ammo. I will not be selling mine!
Agree with Rick on this one. I have had my -1 model for many years. These Gen 3's are just a rock solid & reliable handgun that will handle the nastiest 45acp ammo you wish to feed it.