OK, so as usual, the deeper I get into this, the more confused I get. Let's start with the biggest issue, one I don't know how it's happening. The passenger's side hub is locking itself. I went out to snoop around the diff, and the passenger's hub was 3/4 of the way to being locked. No one else to blame it on, so tried to turn it to free, and it wouldn't go. Not until drove it forward and back a couple of inches would it turn. I verify they're both in free, drive the 3 miles or so to the post office, come home, and the passenger's side is right back to 3/4 locked. Looks like I'll be owing my spotter an apology sometime soon. How is that happening and what do I do to fix that? These are Yukon Hardcore hubs. Haven't been inside them yet, but the outer bolts are all torqued to spec. They turn really easily when they turn, it doesn't feel like there's a lot of grease packed in there. When they won't unlock, it feels like metal on metal and the whole weight of the truck is on there...they don't even act like they're going to move.
OK, on to the front locker. Here's what I know: There is a on/off switch on the dash. It's in the off position normally. With the ignition on, I flip the switch to "on", and I hear a noise from the front diff, either engaging or disengaging. I turn the ignition off, thinking I will hear a noise again, but no, nothing from the front diff, so it's staying in whatever state it's in. If I flip the switch with the ignition off, the second I turn it on, the diff will change status. I turn the ignition off, no change, it stays where it was at. Also, the on line instructions appear to have a plug going to the diff with two wires. This one has a large black plastic box with four wires outside the diff. I can't even find where the wires enter the diff, I think it's behind the box. Box has a circle with a lighting bolt in it embossed on the cover. There is some kind of wazoo plug that attaches the wires to the box, I couldn't figure it out in the dark, and rather than break some little plastic tab that will cost me $40 to replace, I gave up and went back to working on the liftgate for the back. I'll post up some photos in the morning of what I've got going up there, and hopefully will be able to tell you when those wires are hot and where they go...as of now I can just tell you they go up behind the dash somewhere. I'll also find some dirt or gravel somewhere and tell you if the switch is locking or unlocking the diff.