Welcome to the site.
The tag should be on the driver's door jamb on the back side of the cab, at the bottom.
Another way to tell is to see if the sticker is still on the inside of the glove box door. If it doesn't list the GVW, just add the front and rear axel ratings together.
Being a C-50 I'm going to guess it to be at or around 19,500.
Bill
