tons of torque and pretty good mileage.
seriously though anyone Ive heard talk is happy with 4.0. Seems to be a solid engine. I got a 4.0 sittin in the driveway. Just needs to be hacked out of the heep its sittin in.
All depends on how much you wanna spend and how much work you want to do. If you got the cash LS1 would be pretty bitchin or the cummins 4bt. Alot of people go with a 350 or 302. You def need to consider what exactly you want out of your rig and how much you want to throw in it.