3R53-321 – Stub & Midship Shaft – 31/32 X 1.375 Splines – Bearing Dia 1.378″ – Butt Dia 2.625

The 3R53-321 midshaft stub is the center section of a two-piece driveshaft — it carries the center support bearing and bridges the front and rear shaft assemblies. Spline count, spline diameter, and butt diameter are all spec-specific. The 3R53-321 midshaft stub won't fit a different tube OD or a different output shaft spline, and substituting a close-but-not-exact part will produce vibration that traces directly back to this component.

3R53-321 Midshaft Stub — Spline & Tube Dimensions

The 3R53-321 midshaft stub specs: 31/32 X 1.375 spline | 3.500" spline length | 2.625" butt dia | 9.615" end-to-weld | fits 2.750" tube. The butt diameter determines how the stub seats in the driveshaft tube — too loose and the weld joint runs off-center. Spline length determines engagement depth on the output shaft; short engagement under high torque loads damages the shaft splines before the stub shows any sign of wear.

When replacing a midshaft stub, measure both the tube ID and the output shaft spline count before ordering. Check runout on the new 3R53-321 midshaft stub before welding — a stub with more than 0.005" runout will never balance correctly regardless of how many weights you add.

Key Features

• Spline: 31/32 X 1.375 — verify against output shaft
• Spline length: 3.500" — full engagement required under load
• Butt dia: 2.625" — must seat concentrically in driveshaft tube
• End-to-weld: 9.615" — factors into total shaft length
• Tube fit: 2.750" — designed for this tube specification
• Bearing dia: 1.378" — matches center support bearing inner race
• Brand: UDS

Specifications

• SKU: 3R53-321
• Brand: UDS
• Spline: 31/32 X 1.375
• Spline Length: 3.500"
• Butt Dia: 2.625"
• End to Weld: 9.615"
• Tube Fit: 2.750"
• Bearing Dia: 1.378"