Well one question answered real quick, with the Kickdown cable not attached the transmission will shift at the soonest possible moment and will drop into overdrive, its job is basicly when you hit the gas to regulate the pressuere during shifts and when whats say the overdrive is kicked in and you slam the pedal to the floor the cable will kick the tranny into a higher gear hence if in overdrive 4th and your doing 65 and you want to pass grandma you slam it down it will drop out of overdrive into 3rd AKA it will go to a passing gear, this works for all speeds and gears, If you have checked the relays and the sol and your sure these items are working properly and you have checked to make sure the overdrive button is working properly if you checked all these and still nothing you have a bad transmission, theres 2 items in the tranny that will stop the overdrive from engaging 1 is the check balls and the other is the govener i had the govener go out on my 89 AW70L, Good luck though on finding parts for a 72 there hard to find because volvo didnt use them for very long as the 16v engine wasnt there best.