I like the concept of selectable lockers and would probably insist on running them in a late model rig, but for my 89 SAS 4Runner things like tire wear and handling are not as big an issue as long as safety isn't compromised. I run a Detroit in the rear and Aussie up front. The rear has been on the rocks in Moab for about 7 week long trips where the traction of the slick rock likes to bind everything up. The front has survived about 5 of those trips as it was a later mod.
I have seen numerous failures with selectable lockers so opted for ultimate reliability. The rear locker is ok on the street if you treat them right.
