AMERICAN FLYER SILVER BULLET #356 with KNUCKLE COUPLER

I got this engine in 1992 as part of a group lot purchase. I completely cleaned the engine along with cleaning all of the electrical contacts. I put a knuckle coupler on the tender. It had a very good smoking unit.
I had a layout at that time, and I ran it a little for test runs. Since my other engines ran quieter than this engine, I didn't run it very much. It pulled an average length train well, but always had a little variable speed. Maybe the contact with the rails needed to be better?
I would like to pass it on, instead of not using it. Downsized to condo also.