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Discussion Starter #1
Hi, I am considering swapping out my ford 9 inch 3.89 gear ratio, open differentail in my 65 mustang and looking for some recommendations. The 3.89 gears run the rpm's up to high with the 4 speed toploader and I was thinking of dropping down to either 3.50 or 3.25. The car is a non race car but I do enjoy running it hard sometimes but it seems to by running to hard when I get it on the freeway. Also, I am wanting to go to something with a limted slip and am curious what everyone thinks about the ford track lock versus the auburn or others. Thanks
 

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Those are the two best gears for both ends. I actually prefer the 3.25.
 

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My car had a 4spd and 3.50 gear before I installed the 5spd. I agree with olddustyrelics on the 3.25.
 

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Discussion Starter #4
thanks, I was thinking that the 3.25 are probably my best bet. What do you think about the limited slip options. Auburn, ford track lock etc..
 

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I have an Auburn dif with 3.55's and a 5 speed T-5 in my car and its awsome. I absolutely love the combo. At 70 MPH in 5th gear, with the 3.55's and a 255/50/16 tire, I'm at 1900 RPM! Highly recommended combo.
 

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With no overdrive, I would probably opt for something in the 3.25 range. I have a 3.50 traction-lok in both my '66 and my '69. Both have overdrive, so the 3.50 works well on the freeway, but if I put the '66 in 3rd (AOD) or the '69 in 4th (TKO-600) at California freeway speeds, I'm up around 4k in both cars.
 
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