I thought they were no longer -required- on house cars but in
fact there are still house cars in service with them... for example
box cars with roof hatches for kaolin service. I think they could
first be omitted about June-July 1966, but I don't have my data
with me. Lower brake wheels were possible once access to the
roof was no longer necessary but AFAIK there are still cars with
high brake wheels -- but that means tall ladders too. I've never
heard of a rule banning cars based on location of the brake wheel.

Tim O'Connor