Chad,
The Detroit locker does ratchet to allow for slipage and yes, it will clunk, bang, and make all sorts of noise going around turns. It is also kinda hard to set yourself into a turn and then have the locker go into convulsions back there. It loads/unloads the tires making for strange cornering handling.
A traction lock is the way to go for the street. However, the posi clutches do wear out over time. They are replaceable, but it is a PITA to do so. You gotta take the rear all the way apart and separate the actual ring gear carrier halves to gain access to the clutches. It is best to do this when you're setting up your rear end and then you're good for about 50,000 miles, depending on how much cornering you do. I'd say that 99.9% of the 9" posi units you'll find have traction locks. When looking for 9" posi 'pigs' or center sections, look under full size trucks or vans and the old (up to '78) full size cars or station wagons. Generally, the trucks will have better gearing (3.00-3.70 gears) and the cars will be 2.40 (yikes!) to 3.25 gears. Most cars will have 28 spline axles, vans about 50/50, and pickups generally will have 31 spline axles. If you get a 31 spline posi unit, you can swap out the side gears for 28s and you're good to go unless you want to spend the extra bucks and get a set of aftermarket 31 slpine axles because you're surely not going to find original 31s for your car very easily (or cheaply)! You can't just use the truck axles for a couple of reasons. First, most are a 5 on 5-1/2 bolt pattern (except some early F-100s), and second, they'll be much too long for your car.
Beware of the old 50s-60s equal-loc. You can't get parts for them, so once the posi clutches are wasted, you're stuck. Even
I get stuck once in a while!
Another good street posi unit is the Gleason-Torson. They're usually found in the front diff of 4x4 trucks that actually have a posi in the front. Not too common though. They use worm gears in a constant mesh so there's nothing to wear out and they're smooth. I see ads in the 4x4 on off road magazines for them every so often, going for around $450 for the posi unit itself.
Leave the mini spools and full spools to the racers. They do not allow for any slippage, and make cornering a bear. The
tires have to do the slipping!
Oh, and
whatever you do, don't let anyone talk you into making a 'poor-man's posi' by telling you to weld the spider gears!