Metal on Metal Snap sound off rear end

Alright TW I have a issue I just cant figure out.

If I'm coming to a stop or going around a turn at slow speed I'm getting a loud Snap sound out of my rear end. I have wheelers HD 3 leaf add a leafs on my stock springs. They squeek as usual. I can't simulate the pop sound while parked and moving the truck around with my hands. Only usual leaf spring squeek. It's not coming from the shocks (Icon 2.0 ressi's). It almost sounds like a loose brake rotor but louder and the wheels are torqued. The diff fluid is new and clean on last change. I recently broke a rim and had a tire fall off. I removed the rear drum and inspected the wheel lugs after and bought a new rim. Everything looked good and the wheel is torqued to 90 ft LBs. U bolts are still holding a torque of 120 ft lbs. I looked at all the bushing and they are good. Truck has 75K on it. I just tried to put full brake pedal down and 3/4 full gas to almost tire slip and still no pop. Just around a turn or on a slow stop just after first brake application.

The main reason I'm worried about this is because it's not a leaf spring noise I can remake by moving the truck on the ground. It's rather loud and even my wife is scared of it. As soon as you turn or flex the rear end you get a loud metal on metal "POP" that isn't a leaf spring squeek.
Any of you guys with beat up trucks like mine have advice?

 

Possibly a break in one of your OE leaf springs, a buddy of mine had something similar and that was his issue. He assumed that was his issue and ordered dakars to replace the leafs. When taking off the OE leafs during the dakars install, he noticed one of his leaves were broke in half. Couldnt see the break real clear before releasing the tension on the leafs as it was one of the sandwhich'ed leafs.

 

What is the year of the truck?

 

Carefully examine the self adjusters on the rear brakes. I've had them to make all sorts of noise on a few vehicles. Also, is this a TRD Off Road (w/locker) or a TRD Sport (w/LSD)? But, I'd be very suspect of the leaf springs before anything else....