Stamp your VIN on the plate. Attach it in the proper location with the proper fasteners and call it good. Hopefully you won't get the VIN plate expert if and when it gets inspected. Is the truck going to look like a 47.1 and older or is it to look like a 47.5 and up? Personally I don't think you will have a problem since it is so old but you never know.
BTW, the illegal part is changing the VIN plate from the original. That's why re-builders keep the original VIN plate no mater how rough it is.
I am in the same position as you. Only 1 of my AD cabs has a VIN plate. I plan to do just as I've stated above if I ever get one going.
