2303-21 – Transmission Yokes – 21 X 1.100 Splines – 2351-20 Series – 1.495″ Hub Dia

2303-21 -- Toyota Transmission Yoke, 21-Spline x 1.100", 2351-20 Series

The 21-spline x 1.100" profile on 2303-21 is a different Toyota output specification from the 20/22-spline x 0.985" used on 2303-22. Both share the same 5.750" C/U-joint to end dimension and the 2351-20 series U-joint standard, but the hub diameter increases from 1.258" to 1.495" -- this difference reflects a larger transmission output shaft OD on the 21-spline Toyota application. Using the smaller-hub yoke on the larger-shaft transmission risks a loose seal fit and immediate fluid ingress.

The 2351-20 series U-joint specification covers a range of Toyota trucks and SUVs from the 1970s through the early 2000s. Cross-reference the original U-joint part number to confirm series compatibility before installing a new U-joint. If the original driveshaft used a greaseable U-joint, verify the replacement has a zerk fitting location -- sealed non-greaseable joints have a shorter service life in off-road or water-crossing applications.

No counterbore is used on this yoke -- the 1.495" hub provides the sole pilot interface with the transmission output seal. Inspect the seal bore for out-of-round before installation; a distorted bore will allow premature seal wear and fluid contamination of the driveline.