To go into the 75th, SF, or SOF in general as enlisted, what jobs require a secret clearance, and what requires a top secret clearance?

All positions in USASOC require at least a Secret clearance, from the lowest 91B to the 18E running comms

Not entirely sure when it comes to 75th. But, IOT be a 37F, 38B or 18 Series you will need a secret clearance at a minimum. Upon obtaining said MOS then you can apply for a TS if one is needed.

As with everything, "it depends." All will require at least a Secret (or eligible for a Secret), and some positions will require a TS based on sensitivity of information accessible.