I'm old enough to remember when pickups of that vintage were still daily drivers in my youth. Turn signals were not a factory standard equipment, nor option, but were a Dealer-installed option using an aftermarket kit or owner-installed using the same available aftermarket kits. @MrMarty51 is spot on in his remembrance and bringing up the eBay find Signal-Stat. It used the existing rear brake lights for the rear signals and most often used separate, bumper drilled and pedestal mounted round amber light for the front turn signals. They are period correct. I remember when my late father took his '52 Studebaker pickup to the Hershey National car show. One of the judges was going to deduct points for the 'non original' turn signals with the column mounted turn signal unit - until he "reminded" the judge that Dealer-installed non-factory options were perfectly acceptable and not a deductible item.