Brake rotor grooves

[slotard]

I've been hearing a very minor squeal recently. I haven't ever really looked at my brakes, they work well enough, but looking through the wheel I see two grooves. The inner appears to be fairly square bottomed, the other less so.

Is the inner groove an indicator for how far you can turn it?

Any suggestions for what rotors I should go with? It looks like everyone wants to sell a hub and rotor, so not cheap. I'd rather not go with cheap crap, just don't wanna buy parts I don't need. Depending on how the calipers look I might pick up a rebuilt set too. Is AC Delco the way to go for all of it?





It's a '73 C20. Thanks for any help.