Body attachement Bolts
 

In the process of restoring a 1999 GMC topkick 6500 small toterhome, have all the torx heads all over the body all rusted etc. Any ideas on prepping them in place for paint or any type of replacement that is smoother looking.........

Welcome to the forum! If you have the money, I'd go stainless steel. Myself, I don't, so I'd sand them as best you can in place, then coat them with OSPO or equivalent rust inhibitor. Do you know if those are leaking?

They are not leaking, I just cant get to the nut on the back of them everywhere they are located

Look at these https://www.imperialsupplies.com/item/0759400

You need stainless hardware for replacing and they eventually will leak. There is electrolysis going on from mixing steel bolt/screws with aluminum. In some areas I suggest stainless rivets or aluminum rivets, doesn't look like one type fastener to fix all.