There have been several posts about adjustable track bars hitting the diff cover with less than 4 inches of lift.
The stock track bar for your stock set-up is plenty strong. It's usually the bushing at the axle that is the problem, but with 100k miles it's likely that other components are worn. It is kinda painfull to spend almost as much on a good OEM type bar as you would for a good adjustable one, but an adjustable one may just create more problems.
I just replaced mine with the MOOG track bar
for around 100 bucks. It has a heavy duty bushing MOOG Track Bar Bushing
. I replaced the whole thing since there was a little play in the TRE Joint at the frame. (It can be found online cheaper, but Advance Auto Parts had the best images I could find with a quick search)