Try the part number in a Google (or Bing or Yahoo) search. It will be a headlamp from some standard production car or truck of that era. If you can't find it with that number, get the DOT number of the headlamp and search on that. Try a direct search on Ebay too, using the part number or Southwind headlight.
I found headlights for a 91-92 Pace Arrow and that is the sister brand to Southwind. Basically just different trim. These might work.
Also, there are some generic LED headlight replacements that might work for you. Here's one of them: