OK. The only zip locker I'm familiar with is made by Yukon and it is an air locker. It's Yukons attempt to compete with ARB. Yukon does not make it for the 7.5" clamshell so if you go with air, which you should, ARB RD92 is your only choice. I think Harrop is making a electric selectable for the 7.5" now as well.

If you decide to go lunchbox you absolutely should go manual hubs if it's your daily. Once you combine the price of the manual conversion and the cost of the lunch box your damn near at the cost of an ARB and compressor. I personally would never put a lunchbox up front.

ARB's are strong as hell. You will break a chromoly shaft before you break the locker or spider gears. That's a fact that ARB has tested and proven on a dyno. The added benefit of being able to lock only when you want is huge. Steering bind can be severe in the rocks. If you can unlock you can adjust without bind then relock. Lunchboxes don't have that advantage so you just have to power through a shit line.

As some folks around here know I wheel a tiny bit. On trails that some think you need solid axles and 40's to complete. I have used my ARB front plenty of times. I only use it as a last resort. There's times when I've been welly and truly stuck. I flip that little cheat switch and drive right out without correcting anything. They are that handy when needed.

Save your money and get the ARB if you plan on wheeling hard rock gardens. Don't bother with the manual swap. It's not worth it IMO.