Just replaced the distributor core (old one was chirpping and squealing). Found a lot of dirt and sand had gotten inside the cap and worked its way down inside the core, wearing it out.
I do drive through 2-3 feet of water along Lake Ontario, with a lot of waves and sand crashing in on the truck. This must have been when it got inside the distributor.
Anyone driving through simiar situations, including mud/water, may want to seal the cap with a small bead of something. Keep it clean and dry.
I'm a jeep newbie and want to thank this group for the tech support related to swaping out the distributor core...much appreciated. It only took 2 beers!
Jamie.