The only thing I can offer is a link to the "Murray version" of their 1985 GT. Click the link below then scroll down to 85-39004. That was the only Murray GT offered that year, but I believe it shows a 4 prong ignition switch not 5, for that year and the year after.
http://www.mymowerparts.com/pdf/Murray_Models_1968_Thru_1989/
http://www.mymowerparts.com/pdf/Murray_Models_1968_Thru_1989/