Good point Tazza. Still trying to figure it out. With the factory self leveling, the machine does it of course. My thought was that if you had a physical indicator so that with bucket or bale spear on the ground and level, the two lines or indicators would match up together. As you raise the arms, you would still have to adjust level but you would have a visual reference as to where the bucket or spear needs to be to attain level. I will noodle this around some more. Thank you
 
Interesting idea. The mechanical indicators I have seen only work when the boom is down and you want to know when the bucket is flat on grade.
When you raise the boom, the mechanical indicator is useless. Think about setting the bucket level on grade and then raising the boom all the way up. The indicator would still show level, but the cutting edge would be pointed at the sky.
The only idea I have would be to use an electrical tilt switch mounted to the back of the Quick-Tach. The switch would control a light in the cab. After you raise the boom, watch the light as you roll the Quick-Tach. When the tilt switch goes level the contacts close and the indicator light is illuminated.
The trick is to find a switch that will handle the elements, machine vibration and is dampened to some extent.
If you have an old Smart Phone, attach it to the Quick-Tach and run an inclinometer app...
Those old Case 1845's and Toyota SDK7/8's had mechanical bucket leveling. The used a couple of linkage rods and triangular pivots on the boom to keep the bucket at the same tilt as you raised the boom. Dead simple, but the pins and bosses tended to wear and egg out if you didn't keep them greased.