From the Greenberg Guide we have the following:...
Flat Car with lumber: No. 57
...
According to Greenberg the flat with lumber was almost an afterthought and it was the last car added to the 50 series cars.
i guess that also explains the number higher than the caboose. some of the wood load is oddly shaped/ sized, but the consistent patina definitely indicates age so i'll stay as is.
i've seen at least one different color of the gondola (Gravel Car? ... really? was that the Ives term? ... i know Flyer liked to use Sand Car for their gondolas) and many color variations of the #56 caboose, but this set is closely matched in condition. probably originally pulled by an Ives clockwork locomotive, it looks good behind my Flyer cast iron, too.
thanks for the info! ...gary