You are looking at a fantastic addition to your American Flyer collection. This chrome version is hard to find. The chrome on these units is usually rougher like this. I think the randomess of the tarnish makes for a very interesting looking PA PB diesel set. Offered in 1950.
The B unit does NOT have an air chime whistle. It is simply a non-powered B unit.
You can see the light colored plastic shell under the chrome.
CONDITION: C-5+. Serviced and runs. As you can see, the chrome has tarnished like it often does on these units. Drawbar for conneciton to the B unit on back. Not sure if any or all decals are original or repro. The B unit does not have the air chime inside.