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Discussion Starter #1
Hey guys just wondering if anyone runs their 3.8 with 3.55 gears, and can comment on its effect, and how gas mileage is and all that. I do drive about 80 miles highway 4 days a week, so I'm still tossing up 3.27 vs 3.55. If you have some input please chime in!
 

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Motorboatin' SOB, Headlight Cleaning Guru
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dont get 3.55s. get 3.73s. the loss in gas mileage is not that high.

before 3.73s - 400 highway miles on one tank
after 3.73s - 350 highway miles
 

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Discussion Starter #3
yeah but the car has 3.08 stock, I dont want to have a chip burned for 3.73 . And you get around 22 mpg before the gears ( which ones? ) and a little less than 20 with them? I avg about 26-27 mpg or more with 3.08's
 

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Motorboatin' SOB, Headlight Cleaning Guru
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ohh, 3.08s. yep, 3.73s needs a chip. go for 3.55s then.
 

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Discussion Starter #5
got to be others runnin 3.55s with the 6... common guys
 

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To be honest you wont notice that great of difference,, go with 3.73,, I dont car what they say you need to reprogram with any steeper gear change..

I'm going with 4.10's this spring. I think I'm gonna hit the junkyard and get a 7.5" 3.27 in case I go on a trip.. its cake to change out.
 

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Discussion Starter #7
dont have the $$$ for the chip. and it has to make some difference, everyone told me to go gears instead of exhaust lol and i was originally going to do 3.27
 

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Just did 3.08 to 3.55's in a mustang GT last week and even I couldnt tell the diff,, customer wasnt to happy but,, it was a I told yah so kinda thing.

he also had a AODE so it will be the same as yours basically (minus 2 cyls LOL).. It shifted OK kinda early on part throttle and seemed to go past the rev limiter under WOT.. so expect the same.

If it were me,, with a assuming stock? engine.. I would install a 4R70W from a 96/97 thunderbird for the lower 2.8 first gear and install a set of 3.27 gears.

All the benefits of 3.73's with the gas mileage of 3.27's!
 

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The Parts Guy
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If it were me,, with a assuming stock? engine.. I would install a 4R70W from a 96/97 thunderbird for the lower 2.8 first gear and install a set of 3.27 gears.
His car already has a 4R70W. MN12's were never offered with AODE's.


Honestly, you won't notice much difference swapping to 3.55's, but it's your car. I'm running 3.73's in my 94, and I average 21 MPG in stop and go traffic / 24 MPG on the highway.

-Rod
 

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Discussion Starter #10
so basically, its not worth the money and time, now is it worth jumping to 3.27 and going from an open diff to a t-loc one? for about $150? just for the fact it is traction lock and not open
 

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Motorboatin' SOB, Headlight Cleaning Guru
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yes, you can do that. trac lok pumpkins are a semi-hot item for non trac lok cars.
 

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His car already has a 4R70W. MN12's were never offered with AODE's.


Honestly, you won't notice much difference swapping to 3.55's, but it's your car. I'm running 3.73's in my 94, and I average 21 MPG in stop and go traffic / 24 MPG on the highway.

-Rod
You are correct sir,, for some reason I thought the 4R's started in 96',,, I think I was thinking Mustang.
 

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Discussion Starter #13
well thanks guys, guess i'll throw in the new rear and try the gears from there, see how it goes, it has to make some difference, anything is better than what it has in it now, and besides its a trac-loc upgrade too
 

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Confirmed V6 Nut
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mike884,

I have a 7.5 with the 3.27 gears and a trac-loc. I have the 3.55 gears for a 8.8, and when I can afford to, I'll put in a 8.8, the 3.55s, and some sort of Trac-lok. I may get an Auburn or there are other such units I'm drooling over.
 
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