Wiring and QSI install on the 0-6-0The installation went great, and I am very pleased with the sound!Stock wiring:There is a 12 pin plug between the tender and loco. All wires needed for any conversion are available. The tender has 2 circuit boards in it for interfacing, but no extra plugs are provided.As usual, schematics are provided, and as usual, they are wrong. Here they are: Don't worry too much about reading them, it's probably better that you follow what I found, and you SHOULD verify that my findings match your loco.The connector pins in each diagram are numbered from 1 (at the top) to 12.It took a while but I figured out the numbering of the socket pins, it was more difficult because many wires are black at the tender plug.So, if you look at the end of the tender plug, with the locking tab on top, pin 1 is top left, pin 2 is to the right on the top, and so onPins 7-12 are on the lower row, and start at 7 on the left. Remember you are looking at the "business end" of the tender plug. Actual wiring:In the diagram pins 1 & 2 are the pickup from the loco, it only picks up on the first and 3rd axle. Both wires in the tender plug are black, the schematic shows them as black and red, they are both black at the plug, but black and red later. . Pin 1 is red and the left or fireman's side, and pin 2 is black, and the right or engineers side. The schematic has them backwards.Pins 3 & 4 go to the cab light. There looks to be 2 surface mount LEDs tucked up inside the top center of the cab roof. These wires were plugged into B15 on the tender board. I tested at 6 volts.Pins 5 & 6 supposedly go to the headlight and marker lights (but there are no marker lights) These wires were plugged into B3 on the tender board. The headlight is a led. I tested the headlight at 6 volts.Pins 7 & 8 go to the motor, they are much heavier gauge and plug into a large 2 pin molex connector. (very nice). Remember that pin 7 is on the bottom row, left side, under pin 1.Pins 9 & 10 go to wires inside the loco for the smoke unit, I believe, this is wrong in the schematic. I have not opened the boiler yet. In my unit the wires were gray and yellow. Will confirm with a voltmeter soon, maybe I can reach them through the smokebox.Pins 11 & 12 are connected to the chuff switch/cam... this is shown wrong on the schematic. In my unit, the wires were green and blue.The picture below shows the stock wiring. Note:Track pickup wires coming out where the speaker goes.Raised standoffs to lift the speaker over the wires (and not allow the speaker to seal to the chassis!)Cutout in tender shell to accommodate speakerThe "main" tender board is on the rightThe large plug in the upper right corner is the motor wires from the locoThe 3 connectors below the motor connector are track pickup wires, they are connected to the motor socket.3 smaller plugs (green, yellow and red) are for headlight, backup light, and cab light.Below is a closeup of the boards and connectors. If you notice, the row of connectors on the right hand side of the board is basically the internal power buss where the track pickups (top 2 smaller plugs) connect to the motor (top, larger plug). The third small connector brings power over the second board, which only powers the backup light. This board looks to be intended to provide power for a sound card.The yellow connector goes to the backup LED, the green is the cab LED, and the red connector is the headlight LED. Wiring for QSI:The basic wiring is simple.Motor: You remove the motor plug from the socket. Connect to the plug and you have the motor leads. I used two small crimp on pins that went into the socket.Track: Buy another 2 pin Molex plug and plug it into the board in the tender where the motor plug was originally. Now you have the track power pickups from the loco and the tender. (There is some other circuitry connected to this row of sockets on the tender board, appear to be a couple of 5v regulators, I left them connected, they should be fine with no load.)Below is a picture of the 2 "adapters" I made: In the following picture, you see these basic connections to a QSI with the "magnum" adapter.Upper right is the plug from the motor, with wires inserted into it and connected to the motor terminals on the QSI.New plug into the tender board for track pickups.Re-routed rear truck pickup leads that originally came up in the middle of the speaker grill. Just cut them near where the join the other wires (so you have some length), and then route back along the center channel.Now that the pickup wires are out of the way, you can sit the speaker down right on the chassis. Drill out the mounting holes on the speaker to get it to sit down over the spacers, rather than having it suspended up in the air.Lighting is simple. AML runs the LEDs at 6 volts, but I like brighter lamps, so I increased the voltage to get to 10 milliamps. I measured the voltage at this point and calculated resistors which was about 8.5 volts. My power is 23 volts, so 1500 ohms gave me 10 milliamps. I used this on the headlight, rear light, and the cab light. I connected the cab light to the constant output on the QSI board.The wires from the cab light are on a 2 pin connector that is painted green The wires from the headlight are on a 2 pin connector that is painted red The wires from the backup light are on a 2 pin connector that is painted yellowIn all cases the black wires are connected to plus, and the red wires will connect to either negative (cab) or the headlight and rear light terminals on the QSI. (backwards huh?)In my case the motor red wire went to motor - and the motor black wire went to motor plus to give the right DCC direction.The picture below shows final wiring. I chose to keep the stock plugs, but you might want to hardwire the cab, headlight and rear light.I put tape over the wires that go into the connectors to keep them from pulling and any chance of shorts. I have removed the tape to see the connections clearly.I used a 3.5" speaker from Litchfield Station, part number SP-925HP-08. I guess they do not carry it now. Try a Visaton.It packs a lot of bass, but it's so tall I had to cut the projections under the tender hatch off, where there is a place to mount some switches. You can't tell from the outside, and it sounds great, the extra effort was worth it.I used a metal cutoff wheel to slice it off flush inside. Nothing shows from the outside.You have to grind down the sides of the speaker frame to clear the tender shell, just flush with the built-in "gasket" on the speaker. I use a belt sander in a fixture that sets it up like a disc sander.The fit is so tight that just reassembling the tender clamps the speaker in place. Great.The sound is great, will want to put some Velcro or something to keep the coal load from rattling, and something to keep the tender hatch from doing likewise.