Wooden hubs and axles. There are several chips out of the rear of the sides, past the slots.
Pull string, which would be a loop through two holes in the front of the base, is missing.
There are 19 blocks:
2 Doublongs (orange)
5 Oblongs (2 each red and blue, 1 green)
6 Squares (2 each red, blue and yellow)
2 Columns (2 yellow)
2 Pillars (2 green)
1 Gothic Arch (green)
1 Half-Circle (yellow)
More research is needed into the the construction, compared to known 1934-1935 wagons, and if differences are found, it may be justified to date these green wagons to 1932-1933.
See Holgate #??? Colored Junior Blocks, in green wagon.
Possibly a predecessor to #313/314, an 18-block wagon in 1937, which appears to have the same dimensions.