12v lamps are a breeze on a tractor.
on your 8n, look around the dash and cowling area for an unused hole.
hit a store like tractor supply, rural king, autozone, etc, and get a generic push pull light switch with 3 positions, off, front, front and rear ( off, parking, parking and headlamps ). And wire it like that. power to the lamp switch from the side of the ammeter where the key gets it's power, use a lamp switch that has a fuse, then you have 2 circuit, the front lamps and the rear. run the front lamps off the tap that just powers the front, and run the rear lamp off the tap that powers the front and rear. 14awg wire is fine for this. your lamps are likely 30,35, or 55w. that means the max load your switch is expecting is 55x3 or 165w. your bat voltage is 12.6, and charging, more like 14.4.. thus currrent ranges in 11-13a.. so I'd go with a 15a fuse. That will protect your wiring.
Also.. many lamps are made to ground to the sheet metal and only have a single wire for power. Save yourself some headaches and run a ground wire to each lamp and put a ring terminal on it so that it contacts the mounting stem or whatever mount screws that it uses for metal to metal contact to achieve ground. that way you won't be relying on 60 year old rusty sheet metal for ground. your ground wire can come from the battery, where the battery grounds at the frame, or from the alternator body.. many have a few tapped holes on them with a screw/bolt already in them for grounding point.
