If that doesn't work out, try
http://www.dennysdriveshaft.com/index.html This who I use for custom drive shaft work, they balance at over 10K rpms so you get a smooth operating shaft...even with really low diff gearing and overdrive, rarely do driveshaft rpms get faster than 10K...
ie. My Camaro with 3.73 rear gearing and a T56 six speed with .5 ratio overdrive in 6th gear...so when my motor is spinning at 2K, the drive shaft is 4k...
(2K motor rpms divided by.5 OD ratio = 4K drive shaft rpms)