I don't know whether or not that you can replace the actual plate or sticker. The gvwr information can be found on the internet.
A while ago, I found a web site that contains a pdf of the specifications for the 1984 model year trucks. If you send me your email address, I could forward the pdf to you.
You could also request the factory information packets, see this site for details:
http://www.73-87.com/7387info/7387info_packets.htm