I think everybody just wore regular clothes back then, so you probably couldn’t tell any difference just by surveying the crowd from a distance.
In the 30 for 30 Catholics vs Convicts, they talked about how the famous t-shirt was born from the rampant culture of unauthorized game t-shirts being sold everywhere at the time. I remember for a Miami game buying one with Otto stepping on a dead Ibis, fist triumphantly in the air. Was a great shirt, except half the silk screen came off the first time I washed it as well as seams coming apart after drying.
But everyone wore whatever they wanted to games, so the student section blended into the crowd.
I think the authorized apparel being worn by everyone didn’t start being seen until the late 90s when universities realized they had a gold mine on their hands.