If you are standing next to the wheel looking at the face and the threads are pointing to your right and out with Out being towards the outer end of the stud, then they are left hand threads.
If you are looking at the face of the wheel and the threads are pointing out and to your left, then they are the traditional right hand threads.
The studs and lug nuts are marked with an L or a R but as stated the many layers of paint can hide this.
From the factory, the left side of the truck had left hand threads and the right side and right hand threads but someone could have swapped a left hub to the right and vise versa if they weren't watching what they were doing.
Always better to ask around if you are not sure.
Jim
PS: the Willys CJ2A and MB were like this too as well as the early GM cars too clear up into the mid 50's.