You may have just added some insight to this scenario. I don’t know what sequence or who installed the hoses but if it was done at the engine assembly plant, they may have installed this hose on A/C equipped cars. The 257 hose could have been the “universal” hose unless the vehicle had the A/C option. Rather that spin off in another of area of speculation, do you (A12) agree that the A/C cars had this different style of “hump” hose from the factory?