I am gonna say Aussie auto locker for the D30 and if you have the money and a bumper that will fit it, Warn Power Plant. If not I do like the Superwinch brand and most any other Warn will be good as well.
Good Read,...click any product on left side(menu) to see all Reviews. As far as the "Aussie Front Locker", I had various snow days(Pa) that I traveled 40/50mph in 4-HI with "NO" problem what so ever, it tracks awesome, & offroad, totally different jeep.I had'nt thought about one or the other being used as a back-up. Good point. So do you think the ARB would be as reliable as the e-locker?
Don't go with the switch and harness. The harness is cool because it has the right fitting plugs, but put in the wiring and switch outside of the system. Then you'll be able to turn it on when you want. I am also seeing some folks having computer issues when they try to flash the system after the install.I will look into this. I am going to call the shop where i get my stuff and see if they will put the 5.13's in for me. I will need the switch and wiring harness too. Is it pretty simple?