Pet clutch skids on the key shaft to rotate with it. The many gear to the layshaft is fixed with it.  If the still left-hand dog clutch is brought to skid into the left from the gearshift lever, it messes with the clutch gear, plus the upper-speed gear is realized. https://sethnsuts.tinyblogging.com/not-known-details-about-gearbox-auto-77813899