Dan - tell us what kind of tractor you have - you left that out on the profile. I left it out because I ain't got one, yet.
The level indicator is a simple two piece rod & tube deal, with the rod anchored to the bucket, and the tube to the loader arm. When you curl the bucket, it causes the attached rod to move through the tube. The idea is to cut the rod so it is flush with the top end of the tube when the bucket is level with the ground. Then when you are running into a pile, or scooping snow, or something, you can see where the bucket is.
The Old Gunslingers around here may tell you it ain't needed once you get some experience, and they're right. But I'll put one on as soon as I have one to put it on. Now, let's talk about tiltmeters...../w3tcompact/icons/eyes.gif