Is there a "correct" side for side mount?

[lajones]

Other than the rear, just curious if there was a particular side the spare was mounted if only one came on the car. Our budd cab has it on the passenger side fender. The reason I ask is that I have a period trunk to fit the rear of the s/w but that means I will have to do one or two side mounts. I have the fenders for both so I could do both sides but I'm not sure I want to.