Kuhn 1990 GA300GT rotory rake drive shaft

Hi

I need to replace the drive shaft. Dealer asking $925.00 said this drive shaft only was made from 1989 to 1990. Than was changed to a newer design.
Anyone know where to find replacement shaft assembly? Dealer will be my last resort due to huge cost to replace.

Thanks

Kuhn 1990 GA300GT rotory rake drive shaft