Cool.
Is the diameter where the seal runs on the Alliance part the same?
I was told by a Renault guy that CV axles from the Subaru BRAT (known as the Subaru Brumby here in Oz) also fit the Renault output shafts. I think he was using them on a Renault 12. Wouldn't be surprised if the 23 spline was common among other Subaru models.
Also, IIRC, the Renault 16 has the same front track as the Europa rear track.
With some custom rear uprights one could use a stock CV axle from end to end.