You are buying a 1310 Series set of driveshaft slip yoke 2-3-8021KX and splined stub tube shaft 2-40-2051 for tubing 3x0.065" 

2-3-8021KX Technical Specifications:

• Series: 1310 (1.062 x 3.219)
• Spline Dimension: 1.375 x 16 spline
• Length (Centerline to End of Spline): 7.875"
• Dust Cover: Push-on type, for quick and easy fitting
• Compatibility Options: Use 2-3-5821KX for screw-on dust cover, use 2-3-8021KX for push-type cap

2-40-2051 Technical Specs:

• • Series: 1310-1350
  • Glidecote Spline: Y
  • Major Diameter: 1.375
  • Spline Count: 16
  • Involute Spline: N
  • Fits Tube Diameter: 3.000
  • Fits Tube Wall Thickness: .065
  • End of Spline to Weld (K): 7.625
  • Length of Spline (L): 2.250
  • End of Spline to Radius (R): 6.812
  • Butt Diameter: 2.881