The brake line is conductive, made out of plated steel it is a fine conductor of electricity even when muddy. Rust however is not.
Put the earth straps on to frame, tub and engine and then run out ground wires to the solenoid, alternator, instrument panel, fuel tank etc. These old Jeeps need a better ground path than a rusty bit of steel. AMC saved a few pennies by having half of each electrical circuit run through the steel structure, 30 years later and rust and poor joints play havoc with it.
Not as sexy as wiring the power cables but it will sort out a number of electrical troubles for you before they start.
BagusJeep lives in Bali, the Land of Temples.
With a Jeep every prayer counts.
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1995 Cherokee 4.0 - CHEROKEE