One problem related to frame rust has been reported for the 1998 Mazda B3000. The most recently reported issues are listed below.
With 80k on the truck the leaf spring mounts had become oxidized to the point of failure. When this happened my spring came through my bed. There is no body rust, or bed rust. After reading forums I am not the only one with the problem. With 90k on the truck the frame rust through and cracked. There was never a large problem with frame rust before 98 as I have two bronco it's. Ford must have changed steel because there are plenty of guys puzzled with the same problem. Thank you for your time stanley shaffer.