As long as you aren't living in an area that gets a lot of snow and ice every year, I'd see no problem with throwing a "lunchbox" locker in the rear axle, cheap traction! I ran an Aussie Locker in my ZJ's rear 44a for a few years no problem, they aren't super durable (at least not in my case but, it was a street and trail V-8 ZJ with a 231 swap (so all power was going to the rearend whilst on pavement) on 33's with an owner (me) that liked to spin tires!!!) though so, plan on rebuilding it after about 2 years but, parts are cheap and setup is easy since "lunchbox" lockers use your stock carrier. A Lockright would be another budget option. Oh, do be aware though, you will hear and feel the ratcheting action of the locker on the street. (remember the old amusement park rollercoaters that made the click, click, click noise up the main hill? That will be the noise that will accompany your making a U-turn on pavement, at least that was the case with my Aussie) If you have a limited slip factory rear diff, I believe you will have to buy an open carrier to run a lunchbox locker so, figure on some more $$$.
A pricier (but more durable) option would be a Detroit locker. I have one in the rearend of my big truck. As long as you coast/mild throttle around turns you'll hardly notice it but, if you romp the throttle, it will lock up, chirp the tires and (with enough throttle input) kick the back end out. Overall very livable though. (Detroit soft locker is quieter and more subtle (so they say, I have never had one though))
Best choice for a DD/trailrig (IMHO), if you have the money: ARB airlocker! Completely street friendly open diff that locks like a spool at the flick of a switch!!! (I have one in the frontend of my big truck and love it!!!)
EDIT: oops, just read the sub-$500 price range. Lunchbox it is!!! Detroit may still be an option with a little bump in budget though, but don't forget install $$$!
If you already have a limited slip rear diff, I'd look to skidplates instead of a locker. Yeah, the locker makes a big difference in traction BUT, you'll be putting yourself in situations that involve more risk to the Jeep's soft underbelly!!! You'd be surprised at how far you can go even with open diffs, I know stock Jeeps that I have wheeled with have always surprised me!
Last edited by VADERJKU; 05-14-2011 at 12:26 AM.