I have a 99 F-150 2wd. It has a 308 rear end open differential. I would like to change it to limited slip can anyone tell me the easiest way to do this. I would like to avoid having to reprogram my speedometer. Should I get a locker or change the whole rear end? Do they make a 308 that is limited slip?

 

As long as you keep your 3.08s, you will not need to change your speedo. That, and stock tires.

Here is a list of lockers and LS options for you:

Currie Enterprises Racing Rear End Categories

Not sure if you can find a 3.08 in LS, but if you could, that would probably be the cheapest way to go. Downside is a used stocker may or may not have an "limited" left in the limited slip. They wear out, and you won't really know till you try it.

 

Is it a 4.6 or 4.5?
4.6 has an 8.8 rear and 5.4 has a 9.75 rear.
Your changing the diff , not the ring and pinion so yes. You can put a L/S diff in there without changing your gears!