You can't buy guns based on the year made, guns aren't vintages of wine. There are no "good" or "bad" years just good or bad guns.
During the 80's Colt strike quality did fluctuate, but Colt made far more good guns then bad, and everyone else's quality was down too.
When you buy any gun new or old you run a risk of getting a lemon.
I'd suggest making sure the seller offers a standard three day inspection period, and make sure the three days don't start the instant your Dealer gets it.
If it does, make sure the Dealer will let you check it over in the store.