With "mil spec" wiring commonly the entire loom is sealed with heatshrink (something like Raychem DR25) and the connectors are sealed with an adhesive lined heatshrink boot
Raychem DR25 is flexible and flame retardant, is resistant to most fuels (automotive and aviation), brake fluid, diesel fuel, hydraulic oil, lubricating oil and water.
For those interested in the subject have a look at http://www.rbracing-rsr.com/wiring_ecu.html