Wayne, you're right...Athearn & Silver Streak were not associated (got carried away, I guess....). I have a couple of Silver Streak cars that were once my ol' man's from the late 40's/early 50's. Sadly, the flat car is slowly turning to dust - the metal is just crumbling away, as is a little 0-4-0 switcher, that was his first engine. I also have 3-4 Athearn metal cars from the same time period, a tank car, and a Varney hopper. These are all in service with the exception of the flat car.
Bowser did make a run of the Athearn metal cars, in the early 90's, as I recall, and marketed them under the English Model Supply line. I've got 4 of those. All great cars..!!