Identify automatic transmission

mstinaff

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I know that the transmission on my 95 GT has been rebuilt multiple times before I got it. I think I remember being told that the aod-e transmission was swapped for a 4r70w because of availability. But I'm not certain.

How can I identify which transmission I have? And more to the point, how can I tell if the speedometer drive gear is 7 or 8 tooth?

Thanks!
 

07GtS197

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Externally I think they’re the same, the gearing is different though. If you know what rear end gears you have you can use the rpms at a given speed in overdrive with the torque converter locked to figure that out. And the drive gear tooth count, the only way I know of is to physically see it. I guess you could figure that out by checking how many teeth are on the speedo gear and comparing that to an online chart.
 

Wmac

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If you have a 4r70w trans, it would have to be from a 3.8 because of the different bolt up pattern. (4.6 has a different pattern from the 3.8 & 5.0) All 4r trans pans have a sump and the filter has an extension tube on it. Maybe check for a "tag" on the trans, maybe someone could decode it.

Also the ecm would have to have a "chip" because of the different gear ratio's. (mechanical diode)

Best of my knowledge, all T5's from about 92 on, all T45, aode & 4r70w have 8 tooth drive speedo gears. The drive gear is machined into the output shaft of the electronic transmissions and is therefore non-changeable.
 

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