[Brian in PA]

You beat me to it Rod. you also forgot to mention that the crew cab trucks were also the square style until 91 too. They changed the front grill section to allow for the mini quad headlights in the 88- 91 style vehicles. The front clip was different from 81 through the 87 or 91 style.

Brian

P.S. some chevy truck trivia. The 88 round truck style was designated by chevy as the "CK" stlye. What was the previous years called?