4.2 question...
I would go with a V8. I have a 4.2 in the F150 and it needs more power so a 4.6 would be the best choice. I have the Single cab and I would rather have a V8 but I settled with the 4.2. I would definately try to get the other engine. I test drove a V6 X-Cab and I guess it was sufficient but a couple more horses wouldnt hurt.
If you are also getting an automatic, with the combined extra weight of ext. cab and the power loss thru the automatic, the 4.6 or larger may very well be the better way to go...... If not definitely go for the 3.55 rear end


