I've never found a bad one - in a running bike or in a stack of s/h spares. I guess you're just unlucky - or the p/o was keen on doing wheel-stands.
The u/j is NOT replaceable separately - you have to replace the whole shaft assembly.
KBD, The shaft is the same as on a CX500EC (though it has a different part number cast on it), and is probably the same as from a GL500 and GL500I (as they have the same engine mounting position relative to the swing-arm pivot position).
It is NOT the same as for any of the twin-shock models.
The Turbo, CX500EC and GL500I all have 16" dimension from the swingarm pivot-centre to rear-drive mounting face, so the drive-shaft should be the same length. The end fittings are identical, too.