I'm no expert on the MPC annual Plymouth Duster kits, so don't expect much commentary, but pictures of the boxes and their contents I can provide.
Let's start with the 1971 MPC Plymouth Duster "Mild & Wild" kit, which could be built one of four ways- stock, custom, drag or "wild put on". The "wild put on" version consisted of Zingers! style overscaled parts which were all the rage in 1971 and gave any model bedecked with them that zany, outta-sight, cartoony look eight year old boys craved in 1971. The kit was molded in yellow and was a good1/25 scale representation of the real car, right down to the Rallye wheels, 340-4 barrel engine, bucket seats and console.
The 1971 "Mild & Wild" boxes are interesting and different due to the box top art being oriented vertically, rather than the usual horizontal orientation: