I got around to getting a couple 3-5 more pictures of the deck and some details of how it was set up.

Electric controlled hydraulic splitter valves are mounted under the front corner of the frame. The are needed so that I can use one valve on the mill (the one that would run the loading arms) to run both the chains on the deck and the loading arms.
I asked for and thought there would have been some shielding over the valves and wiring. The valves are tucked under the "arm pit" of the frame where they should be safe. But still the wiring looks awful exposed.

The hydraulic hoses and electric cable were run through a 3" plastic pipe. We used quick connectors where they connected to the valves. The cable can be unplugged so it'll be easy to disconnect the deck and move it out. (or plug in a new mill.)
Just goes to show that you shouldn't throw anything out. I had a 16' yellow extension cord that we used on the electric chain saw. Well, I set the saw down one time before the chain had stopped and it whacked off the cord about 1' from the end. I hadn't got around to repairing it or throwing it away. So I wired the sort end into the deck and ran the long end to the switch on the control panel. There wasn't 6" too much cable. I can now just unplug the deck if I want to move it or the mill. (You can see it plugged in in the upper picture.)

The fist lever there beside the switch controls the flow of hydraulics to the selector valves. We drilled a hole in the control panel next to the levers to install a switch to control the valves. It was pretty simple to wire in - even without directions. The toggle UP position works the loading arms. The toggle DOWN works the chains.
If you look close, you’ll note that the shield just right of the switch is missing a stove bolt. Well, we wired everything up and it worked fine. Then we put the shield back on and it wouldn’t switch to the loading arms. “What’s the deal?”. It had tripped a breaker in the circuit. Got to looking and the stove bolt had screwed right into the hot contact on the switch and shorted it out. I should have drilled the hole 1/2" lower. Or I could use a shorter bolt. In any case, it works now.
BTW, this is the same method Wood-Mizer uses to install a deck on an LT40. I noted that the new mill have a hole already there beside the valve body.

The loading arm cylinder has some kind of valve with a knob. I assume it's to adjust the speed of the arms raising or lowering or both. I've not messed with it. I guess I'll need to ask as I didn't get a manual with the deck.