park lights were inside the buckets with the pre-sealed beam headlights, external ones started in 41, if yours has been converted to sealed beams, wouldn't hurt to add external ones somehow ... all lights should work engine on or off, there should be a wire connection to the light switch from the battery, or the battery connection at the ammeter .... not sure on the generator output, but 8V sounds OK .... find a
wiring diagram here in the '38 shop manual
Bill