My name isXXXXX have been a licensed attorney for over ten years and will be assisting you today.
Two things work to your advantage here.
First, that was dismissed. If it was dismissed then it is not a conviction and you do not have to answer "yes" to that question.
Second, the age of the charge. When you start going that far back, the records become imperfect anyway and things do not always show up. Most records were not electronically converted until the late 1990s, if not later. Before that it would be a rare thing for a background search company to go to the expense of cataloging older records manually.
If you've already checked a couple other private sites, it is likely the petit larceny
incident is not going to be on anyone's radar.
To be entirely sure going forward, you may want to go ahead and get the dismissal expunged. The court clerk where you were charged will have forms to do that.
If you have more questions please feel free to ask. I'll be happy to answer them. If you do not, please do remember to rate my service in assistance to you today.