Fuel Quantity Indicator 600 lbs (MD 500?)
This Fuel Quantity Indicator displays fuel quantity from 0-600 lbs (~90 gal), made by Kratos. It has a date stamp of Jun 23, 1978.
We aren't certain, but this may have been used in an McDonnell Douglas's line of MD 500 Defender helicopters, given its 600 lb capacity. The part number on the unit is not legible.
Meausures ~2 inches diameter and ~5 inches long.