Joe - that diagram is general, note it's for 63-72 Buick, if you wire it just like that you won't have a correct ammeter reading - the lamp is the "idiot light" GM had then instead of gauges, the resistance wire is a "fuse substitute" like a fuseable link, and you have no "junction block"
the pics I linked will work for ya, I'll get the exact underdash connections later
Bill
