i know there are 2 pieces of metal on the lower knuckle and lower control arm to keep you from turning the wheel to far, acts as a stop. this could be what your hearing, it causes a popping or a snapping noise. try taking so wheel bearin grease and putting a thin layer on each side of the truck on the lower knuckle. its usualling on the back side/ closes to the door. if i get time tomorrow i'll put my truck up on the lift and snap a few photos of what im talking and youll soon understand, but if you look you might see where metal has been making contact.
I have noticed this at all steering angles from straight ahead to full lock. I have noticed that the popping is least noticeable when straight, and increases with the amount of off center steering. It is a popping sound that I associate with failing struts, or a failing/worn-out upper strut mount.
I have never heard this at high speeds. It is most noticeable when pulling into a gravel parking lot at low speed where the lot is great need of grading (washboard).