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Overdrive Questions

From: Kenny J.
Date: April 05, 2002


I finally found an original type overdrive for my '59 Suburban. It came out of a '58. All that came with it was the dash cable. I have some questions concerning the Mopar overdrive set up from this era: 1.) What year did Mopar go to 12 volts? '55 or '56? I don't want to buy a '55 solenoid relay and find out it's for a six volt car. Ditto the Ford. They apparently used the same relay as Chrysler, so I need to know when they went to twelve volts. 2.) What did the kick down switch look like and where was it mounted on a six cylinder car? Was a special throttle linkage used to activate it or was there a bolt on piece? The '59 parts manual isn't clear on this. 3.) When looking through my speedometer gear chart, I noticed a different part number for overdrive transmissions for the same rear end ratio and speedo gear tooth count. What gives? I am guessing the overdrive transmission's output shaft has a different gear set up. I will retain the 3.73 gears instead of installing the 4.10 gears usually installed on 6/overdrive Plymouths. That ought to help on the expressways. Any help is appreciated. Thanks in advance.


Last changed: July 19, 2018