1940's Switchboard Overall Co. Denim Chore Jacket

I've never seen or heard of this brand before, so I'm not surprised that this jacket ended for over $2K yesterday on eBay! Simple railroad styling, it has no other markings besides the name on the donut hole buttons. Could it be earlier? Possibly, but I could find nothing on this company floating around on the net. Anyone else have some info. on this manufacturer? BTW, the seller had a second jacket of the same brand but lesser condition that sold for just over $860...sort of shot himself in the foot by listing two at the same time I think.