But when you need it to work it will work. It will be the last thing you need to do to your differential. Anything else is not as good.
Note that if you buy one of the used "Nascar" Detroit Lockers on Ebay (and elsewhere) that those units are noisy race spec units, but also work wonderfully on the street if you don't mind the extra "click click click" noise when going around tight corners.
1912 Model T Ford touring Salmon (ugh!)
1913 Model T Ford Touring original Black paint
1915 Model T Ford Roadster Black
1915 Model T Ford touring Black of course!
1967 Cougar GT 390 Cardinal Red / Black
1968 Cougar GTE 427 Augusta Green / Saddle
http://www.supermotors.net/vehicles/registry/15029/50071-2
