I had the same experience with Dynotech. I called them many times, and no one answers the phone. I gave up on them after a couple weeks of trying. I would suggest calling Mark Williams Enterprises. They made a driveshaft for me recently. It was delivered at my house in a couple days after ordering. Top shelf quality, best balancing equipment in the industry, very fast service. Hard to beat in my opinion. Prices are competitive with everyone else, great customer service. For my car, ended up ordering a chromoly shaft with Mark Williams billet 1350 trans yoke, works great, no vibrations, strong as it gets, no complaints.

http://www.markwilliams.com/driveshafts.aspx