The Yukon axle spacer is made for Dana 44 with 19-spline axles and AMC Model 20 applications, intended for standard and Trac-Loc posi setups. Yukon explicitly states this spacer is not for Power Lok installations. It serves as the dimensioned spacer/button required when assembling compatible Dana 44 or AMC Model 20 carriers with 19-spline axles.
Yukon Gear Axle Spacer For Dana 44 19 Spline & AMC Model 20. Standard & Trac Loc / Not Power Lok