YEP this year INDY STK has 153 cars, 3 special cars past champs etc

I hadn't thought of that, all of the National events I race in stock were out west in division 7, but that was back before 1989
I do remember hearing about NHRA limiting the racers on Sunday at Indy, class winners and the rest were the fastest cars in their classes racing on Sunday if they hadn't won their class: work:

25 cars go home before 1st round

The sportsman categories have a designated number of entries allotted at national events.
For Stock and SS, I believe Indy is the only race where that allotment is over 128 cars.
Since they only run 128 cars in those classes, you’re qualifying just to make the show.

At most national events the allotment for Stock and SS is usually 60-80 cars.
Since that’s less than 128....... everyone gets in.......whether you can run the index or not.