afaik the shaft is nla from classicparts
the cup is stil available new from various sources, Heritage, JK, classic etc..
if you need a Petrol cup I believe these are nla, but the diesel one is fine when you chop 10mm off the top of it
for the long term future Ian has paterned the cup so can run some up if required for either fuel
the roll pin 6x32 is still available from VW: N 023 331 1, £1.60ish

I bring this up becuse I've just done a job where the box was in a petrol van converted without the linkage change and it caused it start coming out of 4th gear (couple hundred quid's damage- gear and synchro slider, diesel 4th gears used are selling for over euro100 on fleabay germany now) which customer was putting up with till it broke the 1st/2nd relay lever (which I've never seen before,£5 part, pretty much full strip down to get to it as it's fitted in the main case before the gearshafts go into it)
the difference between the 2wd and syncro versions of the Petrol shaft is quite marked, I've never seen the diesel equivilents together to compare except the syncro petrol and diesel which are fairly different to each other hence the post