The original CPS on my '88 4.0L lasted about 175,000 miles. The second one (factory Jeep parts) lasted about 70,000
Carry a spare.
BTW -- in both cases when mine failed, I had NONE of the "classic" early warning symptoms such as skipping and hard starts. The Jeep ran fine, right up to the time it simply wouldn't start. First time it hit in the driveway at home. Second time was in the parking lot of the local Staples and I had to call AAA for a flatbed.