"Day 2" definition please

[GM-26]

In 1983, I turned 17 years old and purchased my first car. It was a "Day Two" 1972 Chevelle. It had a Cowl Induction Hood, a small block, M-22 and a 4:10 12 bolt rear. It sat up very high, because of big block springs up front and air shocks out back. Cragars all way around and N50's on the rear. It also had bright yellow Lakewood Ladder Bars, a finned aluminum rearend cover and Sun Blue Line Gauges. All the elements of a "Day Two" car!
During that time, my neighborhood had these types of cars everywhere. Especially, since we had speedshops like Motion Performance, Russ' Speedworld and S&K Speed nearby.