Rotation & angle of universal joint?

[Philippe Hurbain]

Assuming the red axle is correctly snapped to the all grey universal joint:

Select red axle
Set rel grid
(single) Select the grey uni end (the one with the blue center)
ctrl+home (reset only ori to grid)
rotate it 90 deg as the axle is X oriented and the uni halves are Z oriented.
add the blue, white end and white axle to the selection
apply script
re snap the white axle to the white end.

OK, it works Problem iI had s that selection needed for the script reapply  is not similar to what we did before. Need to think a bit to really understand...