if you want traction for pulls, go a full out locker, not an lsd(posi). as for towing as long as you're not dropping the clutch and trying to pull from a burnout you should be alright with a spool rear end. the way you're talking about the use your best bet is a selectable. there is no annoying clicking (lunchbox lockers, have one in my jeep. ANNOYING without loud stereo), and anytime you need it its only a button push away. if you're locking the front there is no need for a lunchbox in the rear.