Unlike the Cherokee, either six-cylinder option in the YJ gets you a good engine. Many look down on the ’87-’90 Wranglers because they don’t have a 4.0L, but the 258ci inline-six is no turd. Well, the 258’s induction system is a turd, so plan on a new induction system. There are several kits out there but the two that we’ve used are the Howell TBI kit and the Mopar MPFI kit. The Mopar kit might provide a shade more fuel economy and uses factory Jeep parts, but the Howell kit is less expensive and uses many factory GM parts.