I purchase this Jeep new

Noneed to replace the harness just follow instructions supplied.

What led you to an injector? Chrysler has very little trouble with them. GM has a problem on higher mileage engines because they grab a handful out of a big bin and throws them into an engine on the assembly line. No consideration is given to matching them. Chrysler buys their injectors from Bosch in flow-matched sets so their engines run smoother, especially after they reach high mileage. You can replace just one injector to see if it solves a problem but I'd recommend installing a matched set of six. If you do an internet search for "Jim Linder" in Indianapolis, he puts on very expensive classes around the nation on fuel systems. His company rebuilds injectors, and their most popular product is for GM engines. Many people comment that their engines never ran so smoothly as they do with the new injectors.

If you're trying to solve a misfire or a misfire fault code, rather than replacing an injector, as a test, switch the suspect injector with a different one to see if the misfire code changes to the different cylinder.