According to Summit Racing, you will need the MSD harness adapter [140021AH] in order to connect the 8228 coil to your factory '99 Jeep 4.0L harness.

I have to agree with the others, though. I've read many times that the OEM coil is the way to go.

 

Thank you. Not sure if I'll get it or not but if I do I'll post up some pics and what I think of it

 

That would be great, testimonials go a long way when it comes to what we recommend which is precisely why we encourage people to avoid things like Airtex fuel pumps, Auto Zone CPSs, and Fram oil filters. Some people use them for years without a problem just like some people eat Big Macs every day and somehow manage to maintain a healthy weight and cholesterol. Still not recommended.

 

If you already have the MSD go ahead and use it.. the harness is like $25 iirc.

Easy enough to carry a spare OEM coil in spares bag.. grab a good used one from a partout/junkyard etc.