ZF transmission for my '93: availability of parts?

[Cenobyte]

For quite some time now (couple of years), the gearbox of my '93 ZR-1 is making rattling noises. It started with the usual rattle in 1st, but now the transmission is making these horrible rattles in all gears, worst up to 2000rpm, but also at higer (3500+) rpm's. Sometimes, after a long drive, there is even a grinding noise

At this moment, I'm looking into the options I have, but since I'm in The Netherlands, all ZF/ZR-1 specialists are far, far away

I'm not a mechanic myself, so my only option is to have the work done by a specialist. I have selected a local Corvette specialist to do the repairs, but they say it's almost impossible to get parts for the ZF transmission, besides some standard bearings. What would be my options if I do need other parts in my transmission besides a couple of bearings? And is anyone familiar with this problem in ZF transmissions?

Thanks guys!