Question,
I am selling my 87, and looking at purchasing a 2001 v6 TRD 4x4.
Why are you trading down?
j/k

buy whatever you want. (but it would have been cheaper just to add a ARB to your old Hilux

)
Question about the factory locker. When that is enguaged does that mean that the truck now has posi, or is it still limited slip? Dumb question I know, but I have to ask.
2MK, it only works in low...(but that should be an easy mod to fix

)
And here are SOME vids...
YouTube - ARB Air Locker Video
YouTube - Around the Corner
MONDO IMPORTANE!!!
http://www.youtube.com/watch?v=q-rQTHMVAuw
Anywho...
Lockers [pocket and full case]
Spools
Selectable (ARB and TRD)
& LTD slips...AKA "Posi"
Are all different things. They all have different features, attributes and drawbacks.
Rest assured, a bonafide TRD Electric locker is one of the best, as far as choices go. The traction control, or brake biased "Traction Control"

not even being close in comparison. Your tires are like shovels, and if you have a speed sensitive diff like TC or a LTD slip, often times you've shoveled your way to sitting on Tera Firma by nothing but the frame or axle housing...i.e too late, before the other side gets the message to lock-up or, "hump".
Now, the flip side is, if you're locked up tighter than dicks hatband and you try to negotiate some slick surfaces. You're more than likely going to cause an upset b/c your traction choice has one tire effecting another (L to Right). That will more than likely educe a loss of control...ie. only use lockers when it is necessary. Doing so will also keep the possibility of breakage to a minimum b/c you don't have destructive forces trying to tear your diff apart every time you're trying to make a turn.