I have almost finished restoring the bed of my one. Are you able to link some photos? Typically they rust out at the seams. If its the tray itself then its actually quite easy to unpick the panel and replace (expecially if you say replace it with some flat steel or checkerplate rather than a swaged panel)

some pics here
http://www.mightyram50.net/vbulletin...L200-ClubSport

mine is a NZ built tray, so is a little different to yours but is close enough