A 5 speed is definitely a plus,which ones are most likely to have a locker, SR5 or the limited?
The Limited ones.
Some great info here. I can echo most of it. The 3.4 is like the little engine that could. Its not a rocket ship, but it makes enough power to have a good pickup especially in 4Lo. It is the most bomb proof engine I have ever owned, just don't modify it. The 4cylinder (2.7L) is also very stout, but I would recommend going for the 3.4L.
My 4runner with a rear locker and tires is a point and go vehicle. It can carry a lot of weight now due to upgraded suspension and brakes, and is still small enough to make it down tight trails. Its also easy to park, and the position of the driver almost 50% between front and rear of the vehicle makes driving angles very easy to calculate. I can eyeball some very tight lines while off road in my 3rd gen and usually do not have to make any corrections.
My 80 series is big, slow, and wonderful. I love driving that truck, and that will be the truck I take around the world. It is very roomy inside (but no cup holders), and comfortable for long trips. Completely stock, that truck gets 14 mpg, no matter how it is driven. If you choose the 80 series, you will be taking it in the gas :sombrero: , but there are some obvious advantages. F/R lockers available stock, very bombproof drivetrain, and with a little modification, a very versatile setup (Full time 4wd with unlocked center, 4Hi with locked center, 4Lo with unlocked / locked, and even part time 4wd with some modification to the t-case). These trucks are world renowned for their ability to shrug off abuse, and have earned their stripes in the Overlanding world as the best platform ever brought to the U.S. As long as you are not in a hurry to get there, you will not be disappointed.
My 3rd gen does much better on washboard roads and fast bumpy stuff.