dont those 3.0s get a burnout in cylinder 6?
as far as the diesel, i have heard they have issues and really arent as great as people make them sound.... unless you dump a ton of $ into them.... rumored to be mroe than they are worth.... not to mention initial cost of the engine, might be mreo than your truck si worth....
you could put in a 22re... but be preparred for a full on swap with a donor truck, you will need instrument cluster, and all the wiring basically.... computer all of that....
