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 
MW is the very best in every way. I used lot's of there stuff racing TAD.
But when I needed a new shaft for my street strip 500+ HP BB challenger.
I got it from the local truck driveline shop. They make all kinds of drive/PTO shafts everyday and balance them. Mine was made out of aluminum and it took them one day to make it. It was cheaper than a full on MW or any of the specially shops mentioned here and has held up great in 10 years now.
As far as balancing, they do a good job.
