I would highly recommend NOT doing so, because it will affect your handling. Not in a good way, though. When you go through a turn, your outside tires must travel faster in order to cover a greater distance than your inside tires. Now if your left and right tires are locked together, how are they supposed to accomplish that? Your car is gonna jump and skid through every turn, and it's going to make your car handle like crap.
Drag race guys weld their spider gears because they only drive in a straight line, and corner handling doesn't really affect them. They just want equal power to both drive wheels at all times. And also don't forget that these guys are RWD, but even if you have a locker in the rear end, it's still going to cause the rear of the vehicle to dog track, or hop around turns.
Cliffs: Bad idea.