Shift firmness is control by the vacuum modulator on all 722.3, 4 and 5 transmissions. Identifying the transmission is simple; the oil pan has 6 bolts. The modulator is located on the passage side of the transmission; the proper way to adjust it is with a pressure gauge. Turning the T handle CCW will lower pressure CW will raise pressure. The modulator adjusting T handle has a rubber protective cap over it; it is more then just a cover, it is part of the vacuum system , the cap leak vacuum because it cracks, if it does the shifts may be harsh and erratic. If the modulator can not hold vacuum check the cap first before you condemn the modulator; the part # is 126 277 00 81