1981 e350 cruise control dead

Hi guys Iam new here. did search didnt find anything.My e350 1981 van cruise is dead I cannot find any wiring diagrams for the cruise anywhere. Looked everywhere. even bought ford manual ..nothing on cruise . where 1981 ford f150s come with the same cruise unit or are they diffrent. I cant even find a wiring diagram what gives. even went to library. Iam baffled...Thanks ahead. :banghead: