Coal hopper questions

[Birds]

I was doing some reading on coal hopper history but have some questions.

1) I can't find much detailed information on the "war time" hoppers (hoppers with composite or wood sides and steel outside bracing). Does anyone know if these were very common during the 1940's, and were they still in use a couple years after the war?

2) In coal country during the late 30's & 40's, when a coal train was delivering it's load to a destination (such as a port) would it primarily consist of hoppers from one company, or would a consist have had hoppers from different companies to make sure that supplies were being moved.

As an example:
Would a Norfolk & Western consist have had C&O or Virginian hoppers mixed in with it, or would it all be Norfolk & Wester hoppers?

Thanks,
Birds

[ndbprr]

1) I can't find much detailed information on the "war time" hoppers (hoppers with composite or wood sides and steel outside bracing). Does anyone know if these were very common during the 1940's, and were they still in use a couple years after the war?
I have no factual information but with the country going rigt into the Korean War I suspect they lasted well into the 50's until sufficinet steel was available for panels. War time hoppers were new construction. To the best of my knowledge they didn't strip cars forthe steel
2) In coal country during the late 30's & 40's, when a coal train was delivering it's load to a destination (such as a port) would it primarily consist of hoppers from one company, or would a consist have had hoppers from different companies to make sure that supplies were being moved
Hoppers have always been predominantly one road in trains, An occasional oddball appears but for some reason they seem to like company of their own kind.