Here are some wiring diagrams available for download for the 78 Monza, I am sure other years are very close or the same.
78MonzaWDPage1178.tif
78MonzaWDPage1173.tif
78MonzaWDPage1174.tif
78MonzaWDPage1175.tif
78MonzaWDPage1176.tif
78MonzaWDPage1177.tif