Hello [MENTION=568079]SChis[/MENTION] and welcome to the forum.

Here is a link to your album: https://www.bikeforums.net/g/user/568079

I have only seen a few pictures of an Apollo Concourse. It was probably manufactured between 1980 and 1983. The serial number will help to determine when the frame was manufactured. I do not know the tubeset used for the frame.