Likely the valve body was assembled incorrectly. The Chrysler manual will provide shift speeds for 1-2 and 2-3 for stock engines. The kickdown cable can be adjusted to raise or lower shift points but will not prevent a no-shift to 3rd. If the cable was too tight, then the 1-2 shift would occur at higher speed and likely be pretty harsh. Nope, likely the VB is your culprit.
