You can always add a 5.9 with 60 or 100 or more horsepower to any V8 Grand with very few additional parts. I did. It was very worth it.
Where did you get yours? The best bang for the buck ones I've found have been the Precision Engine ones.
March 2014 GCOTM. 1998 Deep Slate 5.9
On the Jeep:Hot intake, 52mm TB, Summit 8mm wires, catch can, 703s, insulated fuel rails, indexed Champions, Bilstein 4600s, Eibach lowering springs, Moog SS, Ironman mounts, Lotek 2GP, lots of gauges, sparkly paint.
In the garage: M1 4bbl
In the works: Addco/Hellwig sway bars, nitrous, full polly bushings, full exhaust, data logging, billet UD pulleys