Front marker light markings

So ive started the disassembly, cleaning, and cataloging of parts off my 47 KB1. I have a replacement grill that came with the truck since the original one had been hit pretty hard and caved in. As a result I have 2 pair of marker lights. The pair from my truck both have the word "GUIDE" and then a part number 5931859. The pair from the replacement grill have no script at all. Which would be the factory part? Or are they both factory original, some parts just not having any script? I noticed the headlight trim rings also have "GUIDE" along with a separate part number. Not a big deal, but if one pair is reproduction that's the pair I'm going to sell, with the correct disclaimer of course.
Also, anybody know why they'd put marker lights on a truck when there was not a turn signal function? Seems redundant since you could just turn the headlights on. Just curious...

Allen

Also, anybody know why they'd put marker lights on a truck when there was not a turn signal function? Seems redundant since you could just turn the headlights on. Just curious...

Allen

Parking lights were just that, lights for use when the truck is parked on a street. Lots of places weren't well lit.
Marker lights are different, they were on the roof of trucks pulling semi trailers and were there to indicate it was a large vehicle towing a trailer. Same reason for lights on the corner of trailers, to indicate a large vehicle.
The only vehicles with turn signals in the 40's were semi tractors and the turnsignals were mechanical "semaphore" type with a cable and pulley system to raise arrows from the rear of the cab.
The blinky light type turn signal really didn't come into wide spread use until the 50's, so many old vehicle were retrofitted.

IHC bought from several vendors, the guide ones were used mostly, but if another vendor made the same part for them for a few cents less IHC would jump ship with their regular vendor,
no one has repopped these so they are period correct, just unmarked guide or another vendor,

and like CB said sometime you enter somewhere that headlights are too bright, or you just need to be seen, parking lights do that, I always wire my KB parking lights for turn signals,
I'm allergic to drilling holes into the tops of fenders

Thank you gentlemen! Very much out of my wheelhouse but Im learning alot as I start this project.

Allen