A few years ago I had a tour of the Husky Refinery in Toledo, and they still have their original Alky unit from ~1940 in operation.
They now have 3 other Alky units, and occasionally the idea of demolishing the original unit comes up, but it is still an efficient unit and gives operational flexibility for very little cost - so it stays in operation.
Judging by the way the guy giving us the tour was talking, the plant is very proud of the contribution their refinery made to the war effort.