Howe's UJ-3415 joins a 15 mm-29 spline shaft to a 3/4"-30 spline shaft, so you can bridge two different shaft ends without an adapter. Metric end: the listing gives the size in millimeters.
- End 1: 15 mm-29 spline (code 34)
- End 2: 3/4"-30 spline (code 15)
Howe lists this joint family in a long list of spline combinations, so if your ends are different, check the other UJ part numbers.
Howe Performance part number UJ-3415.