Harsh 3-1 2-1 Downshift at Low Speeds

COMPLAINT DESCRIPTION:
Harsh 3-1 or 2-1 downshift when driving slowly at approx. 12-15 mph. then very abrupt 80-90% throttle application.

REMEDY:
Install modified Plate-type check valve with throttle.(13), p/n 124 270 02 89, in shift valve housing of valve body.

NOTE: Modified Plate valve (13) is red in color.