Metal squeal passenger side front...please help

I have a reoccurring squeal that sounds like brake squeal, that I cannot figure out so far I have done the following. Brake pads, rotors, upper control arm (bad ball joint so had to do anyway, lower ball joint ( see upper for rationale), shave pads to ensure no 90 angles, tie rod ends, and I have lubed all slide pins, tried lubing pistons on the caliper. I am at a loss. I cannot see any wear points from metal rub anywhere! What is left? Oh and I did just replace the hub assembly thinking "well maybe the bearing has a flat spot". Thoughts? Please help, I can't seem to figure it out.

I see its 2002 4X4. Have you driven alongside a concrete building or parking lot barriers or has someone zeroed in on the noise as you have driven past them? Have you taken the rear rotor off to inspect the rear parking brake shoes inside the hub? Maybe even the driveshaft support bearing if your model has one. Always had trouble with those on my 97 Ranger

Did you make sure your dust shield isn't bent and rubbing the rotors?

Both good replies. You've seemingly checked the front thoroughly. Exterior noises can be very difficult to pinpoint. Agree with RedRanger7 above, these trucks are notorious for parking brake issues often caused by the linings separating from the shoes. Probably a good time to remove the rear drums to clean and lube anyway. If needed I've read shoe replacement can be somewhat difficult, but many have done it. GL

There was a TSB for a squeaking oil seal on the rear. I don't recall if this was for Gen I or II.

^ Good catch Gavin, but 2007-08 only.

2002 has drum brakes in the rear. No separate parking brake pad like the discs on '03-05. Checking the dust shield in front is a good place to start. I got a small twig caught between my dust shield and rotor once. Gave me a good scare that something serious was wrong. Could be a small rock caught in there too.

Checked dust shield...no rub. No debris. Location definitely seems to be passenger side front. I pulled the caliper and pushed the pistons out by braking with no resistance on it. One piston is moving only. The second did not budge. Then I tried blocking the working one and the other one did finally move but was a real piece of work to get depressed back in. Possibly caliper?? I know the back drums are not it ( kind of know) I pulled and inspected. When disassembled all is usually ok for like 1 day then returns. This is getting to be a nightmare of a find.

I once had a misc metal squeal in the front brakes. Thought it was the dust shield... What it boiled down to be was... the metal shims that you used to set the brake pads into the caliper. The shim was coming in contact with the rotor.