The 1955 1/2 is a made up name by some folks. Then it turns into 1955.5. Then it turns into that is what they were called.
As you can see, Chevy called them Task Force Second Series or 2nd Series or 2nd. The 1955.2 is OK and excepted but it leads towards a decimal unequivalent meaning to second series. I use the 1955.2 because it's easier to type.
It's kind of fashioned after computer versions like 2.0.
Tim and Mike have the correct nomenclature and the GM documentation.
I guess the terms that I had used are "shorthand or slang" for the trucks. I've seen ads and posts in this forum and others using the same "common" speak. I was aware of the 2nd Series or Task Force designations... and of course the Advanced Design....
Also, if you search the interwebs with the tags 1955.1 Chevy Truck / 1955.2 Chevy Truck / 1955.5 Chevy Truck, it brings up the items i spoke of (in my original post) ... lol...
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Facebook is living proof of the George Carlin axiom: "Never underestimate the power of stupid people in large numbers."
It seems to be the bastion of ignorant people, unfortunately giving them a voice and a support network. Hence the lunatic fringe of superstitious and paranoid conspiracy theorists continues to burgeon in the petrie dish of social media.
Upshot: 55.2 is certainly more accurate and understandable than 55.5. 55-2 or 55/2 might be even better.