installing a fan driven unit in Williams Berkshire

That looks like the Lionel "dumb" smoke unit, so my advice is for that model.  The two outside legs on the 3-pin connector are connected together, so you just use either one.  You can connect that to track voltage, the 6VDC from the Williams board for the Seuthe smoke unit isn't enough to get decent output.

I don't see the tube being a problem, I've run longer ones than that with no issues.  As long as it's a reasonably downhill run, you can add smoke fluid through it.  I'd give it a puff of air after adding fluid to clear any bubbles from the tube.

When I do these, I try to mount via brass bracket.  Also you can buy brass tubing to fit the stack.  Trial and error to get the correct fit.

The smoke unit will be grounded if you mount to the chassis, then you only need center rail power wire into the unit.  You can run it from a small switch so you have on/off control.  G

I second the brass bracket to hold the unit in place. I did a Williams 681 and used a thick piece of evergreen plastic. It got hot and sagged.  I had to go back in and use brass. I have doubts that hot glue would hold because those units get pretty warm.

Rob

I tried tubing, it melted slightly changing size, wept oil. Then I used a flanged bronze bushing. It seemed to isolate the tube from the heat better. First JB welded the bushing flange down sealing around the hole, then added a tube. It works, but the tube being smaller than the "stock" opening, it used to work better unmodified. This learned, on another, I drilled the intake hole a bit, and the exhaust a lot, and repeated with a larger bushing, and tube, ensuring that all tubing was larger than "stock". Wow! What a difference! It smokes much better than "stock", and is easier to fill with the bigger tube. 

Putting in an off, or hi/low switch while she's down might be a thought.

thanks for all the insights. Anyone have a photo of their set up?

Here is what I did on mine.  I made the bracket out of brass and mounted an on/off switch as well:

This is how I mounted mine. Keep in mind that there is a plastic flute supplied by Box Car Bill that holds the top on it in place at the stack.  I used Gorilla glue.

Rob

One thing I have always done is ti jumper the two outside pins together on top of the smoke unit board, and I would run one wire to grpund.  It will work better if you can find a plug that will plug in to the bottom of the circut board, then run the center pin to your pickup and the outer wire to ground.  The reason for the jumper is the currant draw can burn the trace on the board into.  Plus it is a simple to do, For the tube I used brass.  If you have to use a flexible tube use a high temp tubing so it will not melt.  I hope this helps.

Ron

I just went back and looked at your pics.  Disconnect the wires at the other end and connect the red wire to the pickup and tie both of the other two to ground,  This will eliminate the need of the jumper on top of the circut board.