Sixteen, been driving about six months and heading home one Saturday morning from an errand for Mom, driving the family's '64 Impala - maroon with silver top and bright red interior, sounds gaudy but it was sharp for a 4-door family car. 327 4 barrel, PowerGlide, driving up the street, playing "stick shift" by moving it to neutral for a quick throttle blip between gears and not paying attention let it slip into reverse at about 20mph!! That thing came to a rapid halt with me hugging the steering wheel and died! When I started it up there was an awful hissing sound coming from the glove box area and it was idling about 2500rpm - no choice but to go home and face the music. I made up some shaky story about reaching for the radio with the wrong hand and bumping the gear shift, and we were off to the dealer. Their lead mechanic listened a second, emptied the glove box and pulled the cardboard liner, and said, "There's a vacuum line back here that popped off of the heater valve. You must have put quite a pressure surge through the system to blow a line off, but everything seems fine. We were lucky this time." As we were leaving he gave me a little smile and quietly said, "It's an automatic son, not a stick shift."