He must have been a proper bowerbird, all the same.
Among the NOS bits are some that are really old; those tin/felt washer sets, that went with the early sintered bush blade [blade P/No 9-024?] mounts, are something I haven't seen for a very long time.
When my family bought a farm/garden machinery business in 1973, there were some of these among the parts stock, but I don't think we ever sold any. That was such a complicated setup, that any mower that came in for service with it, had its blade disc replaced with one that used the then current P/No 9-150 blades, and simpler bolts.