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Mustang rearend got swapped

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Mustang rearend got swapped

Post #1 by paul25g » Fri Jul 01, 2011 10:58 am

Hi guys,

My '66 Mustang coupe, 200CID, 3-speed manual has a door tag that indicates the the original transmission was a 3 speed manual and the original rear axle should have been a 3.20:1. The rear axle in the car has a tag that reads WCY-R, 2 83 5CD 909. In one of the Mustang books I have, it indicates that this is a 2.83:1 Conventional, 2 pin that would have originally been for a 200 engine and an automatic transmission.

My question is, performance wise, what difference does the 2.83:1 make compared to the 3.20:1. Also, I'm curious if the rearend swap could have made a difference with the speedometer accuracy if the speedo gear was never changed? Thanks!


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Re: Mustang rearend got swapped

Post #2 by rocklord » Fri Jul 01, 2011 11:41 am

My first 65 Mustang had the 3.20 gear with 3spd manual and performance was rather lacking. The 2.83 would make it even worse, but great for gas mileage. If you had a 250 in your Mustang, you might be able to get away with the 2.83. The Mavericks had 2.79 gears with the six cylinder (170 and 200) and three speed to help improve gas mileage.

As for your speedometer, if the transmission gear hasn't been changed, your speed would be off. However, you would never have to worry about going over the speed limit :D .
The difference would be the following, speedometer reading/actual speed:
10mph/9mph; 20mph/18mph; 30mph/27mph; 40mph/35mph; 50mph/44mph; 60mph/53mph; 70mph/62mph. (If you're going over 70, you're breaking the law :shock: )
You get the picture.

Hope this helps.

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1965 Mustang, 200CID, 3Spd
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