99 Silverado popping noise

I have a 99 Silverado Z71 with 100000 miles. Only when its wet(rain) and I make a low speed forward or reverse tight turn. It makes a popping noise almost like metal flexing, sounds like it comes from under the drivers left foot. Any clues?? Dealer thought it might be the cab bushings and said something like if that's not it we will work with you.

sounds like it your axle it turns even it not in four wheel drive also it might be front stub put it four wheel on the balk top when it dry and see what it does might help u find the problem.

It sounds more the cross member up front that they were having problems with on the avalanche's.. Maybe go and search through the avalanche forum , there was tons of posts about this poping noise in the front end.