stepside fender install question 83 GMC c15 stepside SWB 350

[juggernaut6625]

Hey guys, so I'm changing the wood in my stepside. While underneath I noticed some rust in spots on the steps and fender close to where the parts meet. I'm taking them off removing all rust the coating with a rubberized under coating to protect them. When re installing the parts should i use any caulk or seam sealer in between? When I removed the steps there seemed to be seam sealer but it was obviously new and poorly installed. I believe it actually attributed to the rust. Was it just application error or is there supposed to be something different there?