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Discussion Starter #1
Hey i am looking for you all to tell me your experiences with your cars and their rear end gears. I am looking into new rear gears for my build and didn't know what to really look for, although im'm leaning towards 3.55 or 3.80, possibly 4.10. Now i have a t5 and 2.80 gears. i don"t know how it drives as it is my project car but I've heard some bad things. feel free to comment what you have and how they work for you and if you have any personal experience with a 289 5 speed let me know:smilie
 

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Hey i am looking for you all to tell me your experiences with your cars and their rear end gears. I am looking into new rear gears for my build and didn't know what to really look for, although im'm leaning towards 3.55 or 3.80, possibly 4.10. Now i have a t5 and 2.80 gears. i don"t know how it drives as it is my project car but I've heard some bad things. feel free to comment what you have and how they work for you and if you have any personal experience with a 289 5 speed let me know:smilie
I have a 289 automatic and 2.80 gears, I am happy with the driveability.
 

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I had the exact same set up, 302 with a t-5 and 2.80 gears with an open diff.

Toss that junk, get 3.80's and a posi. Best upgrade ever.

3.80's are a happy medium between the 4.11's and 3.55's. LOTS of umph and still has good drivability with the t-5, especially since you have the t-5z.

I bought my posi unit from ebay for around $300, it's working fine for me. I'm running summit brand gears.
 

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im running 3.55 trac-loc and a t5 great all around gear. if you plan a little track time go with 3.73, my opinion
 

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im running 3.55 trac-loc and a t5 great all around gear. if you plan a little track time go with 3.73, my opinion
Pretty sure you can't get 3.73 in an 8" only 3.80s


I got 3.80s an trac loc. Yukon brand all around. Love it
 

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I had the exact same set up, 302 with a t-5 and 2.80 gears with an open diff.

Toss that junk, get 3.80's and a posi. Best upgrade ever.

3.80's are a happy medium between the 4.11's and 3.55's. LOTS of umph and still has good drivability with the t-5, especially since you have the t-5z.

I bought my posi unit from ebay for around $300, it's working fine for me. I'm running summit brand gears.
THIS! 3.80s with the T5 work great.
 

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any numbers on mpg?
Not as bad as 4.11's but worse than the 3.50's :)

It's hard to say, you can get very good gas mileage if you're easy on it, but you're going to want to hammer on it quite often.

Ask me how I know ;)
 

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ha yeah well it's a 66 mustang i'm not going to make it a high mpg car but i would like 15 at minimum and not have at it too high of rpm at highway speeds. i have a 1991 foxbody and that does great all around but might want this car to be more aggressive
 

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ha yeah well it's a 66 mustang i'm not going to make it a high mpg car but i would like 15 at minimum and not have at it too high of rpm at highway speeds. i have a 1991 foxbody and that does great all around but might want this car to be more aggressive
Yeah I can get closer to 18 if I'm being gentle.

3.80s sound like a perfect match, anything bigger makes 1st gear pointless even on a t-5z. I can bark the tires threw third gear, you'll like them.

Highway speed RPM is just fine with the over drive.
 

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I have a 66 with a 302 (Alum. heads, aggressive cam,etc). AOD trans. I got a 3.80 trac lock 3rd member off e-bay. Last week I took a cruise with the local club. Forced to drive conservative to stay in line. I got 18.6 mpg for the 150 mile trip. If I play a little bit and run the rpm up between shifts, I can get it down around 10 mpg. Rear tires are 225/60 14 and I'm right at 2500 in OD at 70 mph.
 

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Hwyman,

So your the dirty :smartass: who beat me out of that trac-lock off eBay. I lost out on two of them. I may go with the guy who rebuilds them and sells them for $830 with your choice of gears. He's on eBay.

I have 3.25:1 and a T-5.
 

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Hwyman,

So your the dirty :smartass: who beat me out of that trac-lock off eBay. I lost out on two of them. I may go with the guy who rebuilds them and sells them for $830 with your choice of gears. He's on eBay.

I have 3.25:1 and a T-5.
There are a couple of people on e-bay that do that. Got the whole thing, including the copper washers and friction modifier, painted the color I wanted for about $850 (can't remember exactly). I was having trans work done and the shop let me come down on a Sat. morning and change it out while it was on their lift.
 
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