# 66 GTO Speedometer Driven Gear



## 66 GTO Jack & Mike (Jun 1, 2021)

I am trying to find the factory correct speedometer driven gear for my car.

66 GTO
389 with original factory A/C
Rear end gear 3.23
Tire size 7.75x17

Please help.


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## 66 GTO Jack & Mike (Jun 1, 2021)

3 speed manual (not sure if that matters)


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## PontiacJim (Dec 29, 2012)

66 GTO Jack & Mike said:


> 3 speed manual (not sure if that matters)


You should have the HD 3-speed Dearborn (Ford) transmission. Driven gear is listed as 20 teeth. The lighter duty Muncie 3-speed calls for either a 17 (14" x 7.75") or 18 tooth gear depending on tire size. Stock tire size was 14" x 7.75".


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## 66 GTO Jack & Mike (Jun 1, 2021)

Thanks Jim. Yes it is the Dearborn transmission. Any idea who sells it?


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## PontiacJim (Dec 29, 2012)

66 GTO Jack & Mike said:


> Thanks Jim. Yes it is the Dearborn transmission. Any idea who sells it?


Not really, but my guess would be that it may be the same as a Ford Toploader 4-speed since it is basically the same trans minus a gear.

The Dearborn was the Ford trans adapted to fit the GM cars so a few things were changed. I can't recall if the tailshaft housing was a modified section to fit the GM application, but would think it still used a Ford speedo gear. Find a Ford toploader trans rebuilder/parts supplier and they would be better able to answer the question and even supply you with an assortment of gears.


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