adjustable tracking arm -
 

I have heard a bunch of people on this site say if you lower your truck, you need to put on an adjustable tracking arm. Is there a reason? I am lowering the rear 4" and was going to use the stock tracking arm. Will this cause a problem?:confused:

Re: adjustable tracking arm -
 

Just crawl under there, and visualize what will happen if you move the frame 4 inches closer to your rear without shortening the panhard bar. (It pushes the rear off center in relation to the rest of the driveline...)

Re: adjustable tracking arm -
 

At stock ride height the track bar is running pretty much level. The more you lower your truck, the track bar angles more which pulls the rear axle to the driver-side, which would cause your truck to 'dog walk' down the road.
My truck was lowered 5 inches with stock trackbar and it wasn't that noticeable, but when I lowered it another 2 inches I put in an adjustable track bar to keep the rear axle centered.
You might be ok with only a 4 inch drop and stock track bar.