IMO The best ARBs are the second gen, basically what the zip locker has copied. The first gen was the Roberts locker. Basically an ARB but with four bolts rather than eight in the cap on the carrier. The bolts constantly loosened and the only way to insure reliabilty
was to spot weld the bolt head to the carrier. Those were replaced when the name changed from the Roberts locker to the ARB air locker somewhere in the late 80s or early 90s. The difference between the second and third gen is the air manifold placement.
I much prefered the second gen with the manifold on the non ring gear side of the carrier. The new versions have the supply tube snaking near the ring gear making it very easy to pinch during install. Including the one Roberts, from 1989, locker I still use use in the front of a 60, I have eight second gen ARBs from the 90s and into mid 2000s. The pair I have in one 60 I've had since 96. It's never failed. In fact I've never had an ARB fail.
We ran ARBs in the competion trucks , two FJ40s , both with tires never smaller than 37s an gearing between 140:1 and 200:1 and V-8s.
I've also run auto lockers like the Aussie Locker, Detroit, factory limited slip, factory e-lockers and Lock-Rite. I don't like auto lockers
in snow or ice. Nothing worse than negotiating a icy side hill and your lockers engage. I probably won't buy another ARB strictly
because of the manifold placement. I think most would be happy with the TJM or Harrop. There is credence to the claim that
if the Harrop disengages a little it can effect technical driving the same way a Detroit ratchets crawling over boulders and such.
Auto lockers have that same feel and in competition it is very annoying but unless you are actually in that kind of situation I doubt
you'll ever detect it. You're best going with one of the three or even four, including the Zip, based on customer service and availabilty.
You can't beat Georg for customer service but then we've got Kurt with the same rep. I say buy one from each, one from Georg and one from Kurt, front and back
old design more forgiving with supply line placement
View attachment 2129775
new design runs the air line precariously close to the spinning ring gear from the opposite side