First of all, the Ford N-Series Tractors never had factory installed lights. Lighting kits were always dealer optional accessories. Next, the OEM Ford light switch was FUSED. Just because yours isn't, don't think it was original. Lighting drawings are in the July, 1947 (8N) and after MPC's. Lighting kits contained a more detailed drawing with complete parts list as well. FORD OEM Electrical System was 6V/POS GRN. Wiring used a single power wire with bullet-nose connectors. Ground was made thru tractor metal. Headlights were the 6V sealed beam Tract-O-Lite teardrop style. TAILIGHT used from 39-49 was the TAURUS model, after was the DUOLAMP model. In 1949 Ford released the 8N-15500 Implement Lamp, also called the 'worklight', and also supplied by the CM HALL LAMP CO, Detroit, MI as the FORD Lamp Factory. Up til then you used the RH (per law) headlight as a worklight, but, the new Implement Lamp could be used on the previous 9N and 2N models as well. You need to know how your tractor is wired. Is it OEM 6V/POS GRN or has it been switched over to 12V/NEG GRN? Either way, if it isn't wired correctly you will have starting and charging issues, so forget the lights for now. 6V uses a GEN and a Voltage Regulator. Those get removed and an alternator put in place for a 12V system. 6V industry standard sealed beam lamps are #4019, 12V lamps sealed beam headlamps are Industry Standard #4419. TAILLIGHTS are: 6V - #63, 12V - #67. The Worklamp had its own special 6V lamp and socket. carpenter makes it and a 12V version though. A 1950 Model would indicate it has been revamped to the Angle (Side) Mount Distributor. Prior to 1950 Ford used the front mount distributor. Serial Numbers and what you may perceive as a 1950 model mean nothing. Whether it is a front mount, side mount, 6V, or 12V are the important factors here on an 8N. You can get new, exact-as-original wiring, lights, and parts from Dennis Carpenter.com as he owns much of the original tooling Ford used and is the only licensed by Ford supplier around. You can also get copies of the ESSENTIAL MANUALS which you should own anyway if'N ya wanna be an N-Owner. Here is a scan of the lighting page from the MPC and more info:
FORD TRACTOR OEM WIRING FOR LIGHTING KIT:


OEM 8N LIGHTING KIT DRAWING:

1948 FORD 8N & DEARBORN 10-8 MOLDBOARD PLOW- TIM DALEY OWNER/OPERATOR:

FORD 8N TRACTOR ELECTRICAL SYSTEM BEFORE S/N 263843 (FRONT MOUNT):

FORD 8N TRACTOR ELECTRICAL SYSTEM AFTER S/N 263843 (ANGLE MOUNT):

WIRING PICTOGRAMS by JMOR:

FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:

Tim Daley(MI)