I agree with Egon. I had a bucket level indicator on my IH. It only indicated if the bucket was level with the tractor, not the ground. It wasn't like the tube type ones, though. Imagine this, as I don't have pictures of it....
Your loader arms extend away from the tractor to a point where they then turn down towards the bucket. There are usually two plates at that joint that they welded the two pieces of the arms together between. Bolted to the outside plate was a semi circle of steel about 6 inches across. The bolt was placed at the enter of the circle and it was lose so that the circle could spin on it. There was a 1/2 inch rim along the edge of the circle that faced the operator that had markings stamped into it that would indicate degrees. On the side of the circle that was away from the operator, there was a threaded rod that connected to the bucket. When the bucket was tilted, the rod would rotate the circle and you could tell exactly how many degrees off the bucket was from the plane of the tractor's tires by comparing the degree marks to the edge of the plate that the circle was mounted too. The threaded rod made it adjustable, so you could tweak it for different reasons, etc...
While this was a VERY cool level indicator, it only told how many degrees the bucket was off in relation to the tractor. I found this almost useless in uneven terrain and it was very frustrating. It was easier to just look out the front of the cab windows at the bucket and guess. /forums/images/graemlins/crazy.gif
HOWEVER ... a person(why didn't I think of this) could easily have mounted a steel pendulum with a pointer that would overlap the degree indicator on the same bolt that held the circle that I mentioned. It would always hang down, so that pointer would always be level with the ground. Then you could tilt the bucket so that the bucket level indicator matched the gravity indicator. As you moved forward, your front tires would end up in the excavated whole and your angle would change. The gravity indicator would always be level, so all you would have to do is keep a hand on the joystick and adjust as you slowly moved forward.
That takes care of level, but what about depth?
Mark a stick with 1 inch increments and mount it to your FEL arms so that it is perpendicular to level when the bucket is level. Then set up a cheap, rotating laser level near your excavation. It will flash on the stick, and possibly your eyeballs, so wear the funny glasses. Once you get a small part of your excavation to level and proper depth, mark the stick with black tape where the laser flashes on it. Then all you have to do is keep the laser flashing at the tape level while you also keep the bucket level and off you go.
