It's a tradition that, as I understand it, started back in the '90s to help tell the old Ford trucks apart from the new ones. Somehow it got adopted for use with GM trucks too: OBS stands for Old Body Style, and NBS stands for New Body Style. That's it.
Obviously, this was doomed to become outdated and increasingly confusing every time a new generation debuted. But people have tried very stubbornly to adhere to this system, referring to the generation after the NBS trucks as the "NNBS". You guessed it- "New New Body Style". So what comes after NNBS? NNNBS? New New New Body Style? This just isn't sustainable. It's ridiculous.
And the thing is, we didn't even need this made-up system. GM already had a system of platform codes in place to identify these trucks by generation: GMT400 (roughly 1988-1998), GMT800 (1999-2006), GMT900 (2007-2013), etc.
Whenever you see someone referring to an "OBS" Chevy, they're most likely talking about a GMT400 series truck. Aside from a few exceptions (like Suburbans), this covers model years 1988-1998.
Thanks for the explanation. I've been discussing old Fords on message boards for many years and I've never seen that. The style I have (and discuss the most) is called a Bumpside, '67-72. What came next was the Dentside, '73-79. Other styles are the Bullnose, the Slick, the Box, the Fat Fender and others. There must be a few dozen Old Body Styles in Fords alone, right?.
Yeah. Ford's now in their 13th generation of F-series trucks, I believe. I really do like the old nicknames like Bullnose and Squarebody, but I can totally understand why people would gravitate towards a shorter acronym to use on forums and such. It's just a shame that "Old/New Body Style" caught on like it did. Especially when GM already had an official shorthand system for their truck platforms.