Here is my problem when braking firm or soft when truck is almost at a stop makes metallic rubbing sound from rear. Check brakes good pads good rotors good caliper slides good?

Ebrakes look good nothing stuck in it. I am stumped

 

I know you said E-brakes were good, but even if the shoes are still good, sometimes a little rust / dirt / etc works it's way into the parking brake cables that live in a splashy area and they don't always fully release. Make sure parking brake is released in the cab, then try grabbing them cables and shaking vigorously and then without touching the parking brake, go for a short test drive. If it works ..... spray the cables well with Brakleen or or WD-40.

If that doesn't change it, try spraying the rotors and pads with some CRC Brakleen . If I was doing it, I'd remove a wheel, gently open the caliper a little so I could spray the face of the pads liberally including any grooves. Blow dry and remount wheel, pump up brake and then do other side same way.

While there ..... look really close at both inner and outer pads (if not already done so) up close.

Good Luck ....