Yes. If it's a Detroit style locker rather than a selectable locker you migh be giving up some safety on the street. The VSC would probably have a harder time keeping up with a locked rear axle. How hardcore do you wheel? The ATRAC seems to work pretty well for most. I don't think a US spec '04 would have a limited slip. It does have limited slip functionality via the brakes and ATRAC.
:cheers: