The third generation model continued on by carrying V8 engines only: a 5.7 HEMI and a mouth watering SRT-8. The former was dropped in 2009 with the higher powered brethren remained.
The second generation Grand Cherokee was only launched with a 4.7 V8 gasoline. Aside from the removal of a traction control (weird, eh), not much changes had occurred.
Receiving a mid-refresh cycle this year, the Grand Cherokee gets a diesel engine while the V8 can be ordered upon request. It rides smoothly but you can only hitch four friends and a little amount of cargo. Go elsewhere if you need that required third row.