Detroit rear locker

What Clax said , works for me and has done so trouble free for a long time .

Same as above

Ditto

I concur.

So what would you do first? Front or back? Mainly sand driving

Put the locker in the rear first , it will give more advantage than the front .
The front is the iceing on the cake .

I put it in the back because I figured it would assist in a wider range of situations than in the front, which would mainly be for steep climbing.
Also, a Detroit locker can affect the steering if in the front. You need a Tru Trac version for the front.

Auto unlockers do not go in the front of constant FWD vehicles. You cannot steer because of the locked diff. Detroits etc in the rear only and a manual lockable diff or LSD type in the front.

Garry

True, but Tru Tracs can go in the front.

I have test driven a disco with a true track in the front and steering was great