USAir DC-9

[wag]

I'm pretty sure Delta is still flying some DC9-50's as well as MD-80 series. We used to have North Central airlines flying various DC-9 versions, then they became Republic airlines, who were purchased by Northwest airlines, who in turn were purchased by Delta. So we've been seeing the same DC-9's around here for more than 40 years, just with different paint schemes.
Wayne