Not sure how it works with the later trucks, but it's my experience with the '41 thru '53 trucks that there is little difference between the 3/4 ton and 1 ton trucks in regards to location of the eBrake lever or other largely 'cosmetic' things.
From a quick glance at the TechTips section here on the bolt, it looks like in '58 and '59 they only made one kind of 1 ton truck.. it had a 135" wheel base.
If the VIN/Serial number is unreadable, that might be your only real clue.. but i'm sure somebody with a lot more knowledge in that area will be along with more helpful hints.
