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I'm currently running a carb'd 383, th-350, a stock 3.08 rear end on my '68 and 235-60-15 rear tires. In the winter I plan on upgrading to a stage 2, 200-4R from Bowtie Overdrive. My question is this, can I get away with a 3.55 posi rear end without stalling the **** out of Breanne or do I need to run a 3.73 minimum?
 

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In most cases if running a 24-26" tire in the rear guys will run a 3.42-3.73 gear. If you have a larger cam and stall or taller tires then lower gears may be in order.

Miles
 

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3.73s

go with the 3.73's. You'll be further into that power band without the tranny lugging the motor. Also, are you going to be running the lockup? That makes a difference as well. then also how you have your TV cable adjusted. Depending on how much throttle you need to give it to kick down if need be.....again though, Id lean toward the 73's.
 

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Discussion Starter #6
go with the 3.73's. You'll be further into that power band without the tranny lugging the motor. Also, are you going to be running the lockup? That makes a difference as well. then also how you have your TV cable adjusted. Depending on how much throttle you need to give it to kick down if need be.....again though, Id lean toward the 73's.
I feel dumb right now... I don't understand what you mean! lol
 

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no need to feel dumb

NPHNP
the lock up option will be for the O/D transmission locking up once it goes into overdrive for more efficiency. (bowtie will ask which version you want to run) I've found that it also drops the RPM a few hundred when it does lock up which is why I asked. I wouldnt want the engine running right at where you are making power, say 1800 rpm and have the car constantly feeling like its bogging down and constantly having to make it downshift cause its not making any power. My pickup that I just swapped a 700R4 into is doing that right now. After all the 200's and 700's Ive installed, you want to give yourself some elbow room on the low end. Make sense?
 

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3.55's

I have about 400horse 383 700r4 and put 3.55's and eaton posi
It is rowdy and fun to drive with cbr suspension up front
Car has 255/60/15
I recommend 200r4 over the 700r4 but since my friend did it he pushed me toward the 700r4.
It's got 2500 converter
I think 3.42-3.55 are great gears

I love it!
 

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I ran a 200-4R, 3.42 gear with 26" tire in my 49 Chevy coupe.

It ran fine but I think there was room for more gear - like a 3.73.

My son presently has the 4L60E, 26" tires, and 3.73 gears in his 68. Its a very nice combo.
 
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