Here are some of my notes for these vans:

1971: Blue bowtie logo in grille

1973: Gold bowtie logo in grille

1977: New badges on fenders and rear door
Rear door badge has a black box background

1978: New front end with eggcrate grille in 5x3 pattern
License plate moved from rear door to bumper

1980: Revised grille in 11x3 pattern
New door mirrors on single base

1981: Badge on rear door lowered to bottom of door

1983: New front end with grille with thick horizontal bar but bowtie is larger
Grille background is in 8x8 pattern
New door badge design, 2-line lettering
Stacked headlights available on higher trim levels
New rear badge, no box, but chrome underline

1984: Swing-out side doors are new option

1985: New grille, horizontal bar thicker, same height as bowtie
Grille background is now in a 8x4 pattern
New larger taillights

1987: Fuel Injection badges

1990: Extended version is now available

1992: Restyled front end, two different grille patterns
Dual headlight models have two horizonal bright bars over 10x6 pattern dark grille
Quad headlight models feature side-by-side headlights over large turn signal, grille pattern is one large horizontal bar over 8x6 dark back grille

1993: ABS available

1994: Rear badge move from left door to right door
CHMSL

1995:


I'm sure I'm going to find others to add and revise