It's always best to replace the entire pump/sending unit as a single module. It easy to damage the sending unit or cause fuel leaks with the new pump. More money, but you won't have to go back in a second time.

There is no lift pump in a 97 K-1500.

If your fuel gauge works, the sending unit is ok. Just replace the pump and the "sock". It's a prefilter.

A 'sender-unit' in the fuel-system, is what tells the gauge how much fuel to show on the dashboard.

You may be thinking of a low-pressure 'lift-pump', which feeds the high-pressure fuel pump

replace whats not working,