Man that's expensive. Hopefully someone has a used one on here...nothing is wrong with the stock one I just don't know how it will hold up with some upgrades.
A few people have installed a 93 MarkVIII driveshaft in the AOD cars without shortening it or anything.
Jeff Bratton is one I know of for sure. He has not had any problems that I know of.
If it's just that you're worried about tearing the old one up....don't worry!!