Early Athearn HO Kit Flat Car With Southern Pacific Trailers Circa 1960

This is a very early Athearn kit perhaps from the mid 1950s or so. The unique feature of these are the couplers with the tiny springs. Sadly my box fell on the floor and the carpet monster ate the tiny springs. Just as well as they are said to be such a pain they are best relaced with any of the newer couplers. Also this is a yellow box instead of the normal blue box so this is a very early Athearn model.
In the meantime I really like the Southern Pacific trailers.