I have a 1956 C180 with 92 gallon Monarchs. It’s got the old wing root mounted sight gauges.

I’ve also got an older fuel totalizer that works pretty good.

Is there an individual 4 tank indicator system I could put in?

Do you have Monarch mains or bladders? As far as I know the Monarch mains all came with a hole on the inboard wall for a sending unit. Do you have pumps for the aux tanks? I believe aux tank pumps were required to feed main bladders whereas the aux can gravity feed Monarch mains so only two fuel gauges were required for each wing. Call Hartwig. He may or may not help you. If you have bladders you may need to have them reworked or replaced to accommodate the sending unit.

They are gravity fed monarch mains. I’d like to have accurate quantity indication in each tank. So two per wing as mentioned.

I’ll give Hartwig a call as well as Cies.

If you have gravity fed mains, the aux and its corresponding main will always be at the same level. So you only need a sender in each main. Get two Cies senders and a digital gauge and you’ll find it accurate to within gallon or better. Trying to install and calibrate aux tank senders will add expense and complexity with very little to no additional accuracy. The only caveat is when not topping off. If you’re not topping off you need to add to the aux only because the check valves only allow the tanks to level in one direction.
The key to accuracy is the calibration which is very tedious and time consuming. Starting with dry tanks and adding 1 gallon at a time to the aux only and waiting for that gallon to stop moving. It takes about 10-15 minutes per gallon.

That’s not entirely accurate. Gas most definitely can flow from the mains to the aux tanks with gravity feed monarchs…even with the interconnect flapper valve properly installed.

If your existing fuel computer works fine, just use it. If it's a good one, it'll always be far more precise than any guages. Assuming you input data properly.

I have used JPI instruments for ~ 40 years or so, and they have always been magnificent. But, as I noted above, garbage in, garbage out.

When I was operating 185s and 206s with 80 plus gallons of fuel, and only infrequently topping off, but fueling frequently, it always amazed me when I did top off the tanks, and doing the math realized that the computer was only off by a gallon after twenty five hours between top offs. Using calibrated fuel source gauges of course.

I haven't really paid much attention to gas guages for years.

I personally opted to keep my wing root mechanical guages as a backup to my very accurate GI-275 totalizer with EI fuel flow gauges. CIES senders seem great - but you remove any possibility of redundancy by installing them because it requires removal of the wing root gauge.

Does Hartwig still make a 92g system for the early (53-59) skywagons?