rear leafs
Assuming you mean the rear spring hangers are rusted through...replace them. Very common problem on this vintage Ford truck. I replaced mine in my home garage using a 4.5" angle grinder and some cut off wheels from Harbor Freight. I purchased spring hangers and hardware from here: Leaf Springs and Suspension Parts by Auto and Truck Springs
You can get new leaf spring hangers and shackles from NPD, LMC, or Ebay. The dealer may even still have them. Make sure if you have to cut or drill out the rivets you use grade 8 bolts and not the cheapo hardware store bolts either. Go to Fastenal or a good supplier.
That is why I like the spring hanger kits from the site I posted, they include all the hardware. Dorman used to have a similar kit, but they tend to be in perpetual backorder. Worth a shot...









