The correct spark plug gap for a 1989 Jeep Comanche depends on the engine it has. Jeep Comanches of that year came with several different engine options (e.g., 2.5L, 4.0L). You
must consult your owner's manual for the precise specification.
Without knowing the engine size, I cannot provide the correct gap. Attempting to use an incorrect gap can lead to misfires, poor performance, and engine damage.