Is this all I need to put a whistle in a tender?
You need a way to control it, like a whistle relay. This is a “slugged” relay, which responds to the small DC voltage put out by the whistle control, but not to the 60-hertz AC that powers the train (and the whistle motor).
Be sure to mount the whistle so that the air intake, on the bottom, is not blocked. If the tender is completely enclosed, you may also need to create an unobtrusive opening or two to get the sound out.
What if my traisformer has a whistle controller?[;)]
You still need a relay. The whistle controller is really just giving a slight DC voltage to the AC sine wave, which is what the relay responds to to blow the whistle. Without a relay, the whistle will blow constantly, which you don’t want.
Postwar whistle came in two styles, horizontal mounting and vertical mounting. The one above appears to be a vertical mount rather than a horizontal mount. Two screws would extend through the tender floor to holes in the bottom of the whistle unit. The relay hung from the tab at the top. I’ll get a picture of what one looks like installed in a few minutes.
Here’s a horizontal whistle
And here’s a verticle whistle, like you picture above
If this whistle is intended for the tender you pictured in your earlier post, the verticle whistle is the correct one. The tender pictured with a verticle whistle installed is a 2466WX, which should be pretty much the same as the one you already have. The correct mounting and air holes may even already be there. Just be sure you also get a set of trucks with pickup rollers, and a relay.