I'm not quite sure what this means.  :-)

Possible choices are:  1 = S (E)
                       2 = Dakota, Dakota Sport, Dakota SLT (AKA: Base (L))

The choices for 1989-1991 appear to be slightly different:

                       0 = 100
                       1 = 150 or economy (E) on Dakota
                       2 = 250 or low (L) on Dakota
                       3 = 350 or medium (M) on Dakota
                       4 = High (H) on Dakota
                       5 = Premium (P) on Dakota
                       6 = Sport (S)
                       7 = Special (X)
                       9 = Shelby