1203-18 – Transmission Yokes – 1251 Series – 18 X 0.800 Splines – 1.178″ Hub Dia

The 1203-18 addresses the smallest-spline configuration in the 1251 Nissan/Subaru lineup: an 18-spline, 0.800" PD interface used on lighter compact applications. The 1.178" hub OD is unique to this variant and requires a correspondingly small tailshaft seal -- standard 1.375" or 1.495" seals from other Nissan applications will not fit. This is one of the narrower output shaft specifications in the 1251 series and should not be confused with the larger 22/24-spline variants when sourcing a replacement.

• 18-spline x 0.800" PD -- lightest-duty 1251 Nissan spec; confirms compact passenger car or light-truck application
• 1.178" hub OD -- source seal specifically for this OD; no cross-over to other Nissan yoke seals in this list
• 0.910" counterbore -- pilots over small bearing retainer; confirm retainer OD before pressing yoke on
• 4.875" C-to-end -- compact dimension; suited to shorter-wheelbase Nissan platforms
• 1251-series U-joint interface; pair with a transmission yoke of the same series for consistent strength

Tip: with a hub OD under 1.200", oil contamination around the seal area is often misdiagnosed as a seal failure when it is actually the yoke hub that has corroded or mechanically grooved. Clean the hub OD carefully and measure with a micrometer -- if the hub is worn below 1.170", the seal cannot maintain contact and leaks will continue regardless of how many seals are installed.