1984 should be a TH200C with lockup. There will an electrical connector on the left (driver) side. It will have either 1 (internal al ground) or 2 pins (external ground). Make sure you can get your money back if it’s not rebuildable. Use a shop that is performance oriented to the TH200 like REMAC. ATI or Turbo Action who make cast alum pans for these trans may be able to recommend a shop in your area.