Baby Boomers! Obviously you got "baby boomer" years incorrect. The early 4 speed hydramatics shifted to 3rd and 4th gear when in LO position and floored. And the hydramatics were designed in the 1930's, so these automatic upshifts were being done way before baby boomer time (1946-1965). Also, my 4L60E sensed high rpms when in 1 and automatically shifted to 2. It was in a 1998 Silverado. GM tried to prevent engine damage, at least on hydramatics, but obviously not all of their transmissions.
