Okay...I have a 2.5 that I have no idea how old it is..or how much fuel has been through it. I've cooked it a few times cause I had never run one before and it is runing fine. My son has a 3.3 and it seems to have more than enough power to pop the front end at will. Unless you are planning on racing, or want to be the "bad" boy on the block, these engines seem to have enough(2.5) or more than enough(3.3) power for bashing and having lots of fun. I really like the engine that Rolex has suggested because it is cheap and offers more power, but probably will not tear the drivetrain out of the truck.
I guess what I am saying is YOU have to decide what it is that YOU want to do with your truck (race it or have fun with it). If funds are an issue, then a .26 red dot is probably not a good choice as in the long run you are looking at about $400 - $600 to actually run it, as it WILL tear the drivetrain out of a stock truck.
Just my opinion.....