Thanks Andrew.

Real OEM provided some detail, but not the full story. It gave me two part numbers for the entire rear prop, a superceded part and the prop I had fitted
7 529 661 A103.

So what I've discovered mainly by trial and error is that the rear section of all the props I've found so far are in fact the same length. It appears that the front section of the rear prop is the part that is a different length depending on the transmission/gearbox fitted. Its a very simple job to split the prop into its two halves, just a 18mm head bolt that sits in the centre of the splined yoke and this can be accessed with a flat ring spanner down in the gap in front of the UJ.

Anyone on the search for a used 6sp manual prop, which are like hens teeth over here at least, can simply use a back section from the auto prop which appear to be everywhere for just a few quid and replace the support bearing and guibo on the front half of their own manual prop and away you go.

What a shame its not really practical or economical to replace the UJ on the prop as they have no C clips holding the UJ cups in place, instead they are machine spiked after assembly. I know it can be done but not really in the realms of a back yard muckanik!

Hope this may help someone searching for a cost effective prop repair on a manual 3.0d e53.