When I said automatic locker I meant it does not need the driver to engage it as it is already locked..or at least that's my understanding of it..
from what I have been told a detroit is better described as an unlocker not a locker as it is already locked. the detroit i think simply allows a differential in speed much like a normal diff (although I'm not sure but perhaps a significant load of difference in speed is needed)so the car is able to corner but when on the straight is permanently locked....I could be wrong here but I think people get similar results from welding up there rear diffs..I have heard of people doing this in the UK however I believe they wreck their tyres as the car doesn't/can't corner well
I could be talking out of my arse though and I'm sure someones fingers are burning right now to tell me so:D

