FordGirl,
Before you even think about bigger tires and lockers/LSD, please look on the drivers side door jamb and under "axle" there is a 2 digit letter/number or 2 numbers. this is the axle code. Can you tell us what this code is?
It won't do you any good to put bigger tires of the gear ratio is too high. Your truck will be gutless, plus if you have to change gears then that is the time to put in a locker or Limited slip. They will put the locker/LSD in for free if you are changing gears.
Trak-Loks are cheap, but DON'T Last, and won't give you the traction that you would need, since you only have one axle that drives.
What makes the ARB "air locker" so good is that you can engage it only when you need or want to. If you are concidering a limited slip, I would suggest an Auburn or Auburn Pro. Otherwise the ARB, Powertrax, or even a Detroit lockers would be much better.
You gotta remember, you get what you pay for, and modifying a truck IS NOT A CHEAP THING TO DO! by the time I finish with the first portion of my truck, I will have invested around $7000.00 and that's just for a 4" lift, 1" body lift, a new HD transfercase, gears, ARB locker in the back, limited slip in the front(the only thing available for 95+ models at this time),35X12.5 R15 BFG KO's,ER-117 wheels and labor.