Sheet Metal Question

[belairbob50]

I have 2 sheet metal panels that I purchased for a 1950 Chevrolet some time ago. Recently, I discovered that they are not for this vehicle. They have a GM parts tag attached with the part number 385483. These panels attach to either side of the radiator and to the front inner fender. The air duct hole for a Chevrolet is 4 1/4" - these have a 5 1/4" hole. That is why I am thinking they are for a larger GM vehicle like Cadillac or Buick. In the Chevrolet parts book, this type of part is listed in group 8.153 as a skirt-panel-extension-spacer-support-shield-retainer plate-front fender part #3688519. I have attached a photo for a better description. I am looking for information as to what these might fit, or point me in the right direction as to where I should look. Thank you.