[hharney]

There are no dipsticks or tabs that work for fuel capacity on the skymaster. The original system with separate aux tanks did not allow a dipstick to be used either. Although on the original system I suppose you could make up something for the aux tanks because they are single units.

Fuel totalizer would be best option. The Shadin system is a good direct replacement for the original fuel flow from Cessna but if you want engine analyzer features it might be cheaper to go with JPI with fuel flow built in.

The fuel gauges need to read empty when tanks are empty. It's always good to know that the gauge is accurate. De-fuel the tanks and find out. Then as you add fuel back in you can verify the gauges.