I have a Z1 Platinum Aluminum driveshaft for a 5spd TT ($388 on Z1's site). I bought it from someone thinking it was the regular kind w/ the CV joint ($330). This is for a (someday) daily driver so I care much more about noise/harshness than weight/performance.
Despite the $58 price difference, Z1 won't let me swap out without a restocking fee and paying shipping both ways. I was hoping if you have a new one, or are about to buy one, you can ship it to me and I'll ship you the aluminum one (brand new, still in tube from Z1) straight up.