8 3/4 question

Below is from Moparts Tech Archive

Strength Considerations

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Pinions...

The 1-3/8" '741' pinion is the weakest. It is still a capable unit in most

moderate power, moderate traction street applications. For high torque

applications with high traction tires, the 1-3/4" or 1-7/8" should be

considered.



The 1-7/8" '489' is supposedly the strongest. Although the stem tapers down

along it's length, it appears inherently stronger from a pinion stem

perspective and the inherent strength of the fine splines (OEM gears).

The 1-3/4" '742' has a larger rear pinion bearing yielding greater strength

in this area. The 1-3/4" shares yoke mount diameter and mounting nut

with the 1-3/8".