Find the Rearend Gear Ratio
Short answer: Two ways. Read the code: the two-letter code on the rear of the driver’s-side axle tube (halfway between the drum and the “pumpkin”) — wire-brush to read it. Or count turns: chalk-mark the driveshaft yoke and diff housing and the tire; rotate the tire and count driveshaft revolutions — ratio = driveshaft turns ÷ tire turns (e.g., 17 ÷ 5 = 3.4:1).
| Posi | Open | Ratio |
|---|---|---|
| UN | XB | 2.56 |
| UP | XC | 2.78 |
| UR | XD | 2.93 |
| US | XE | 3.08 |
| UT | XF | 3.23 |
| UV | XG | 3.36 |
| UW | XH | 3.55 |
| UX | — | 3.90 |
| UY | — | 4.33 |
For reference: Powerglide 1st 1.76 / 2nd 1.00 / Rev 1.76; TH400 1st 2.48 / 2nd 1.48 / 3rd 1.00 / Rev 2.00.
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Content last modified: June 13, 2026 at 10:06 am
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