I used Dynotech in Michigan after hearing good things, but was not impressed.
Showed up longer than ordered, and they said they felt it would be fine, it wouldn't have fit in the car let alone work under suspension movement, So they fixed it, shipping on my dime, then it rang so loud I though I had a bad rear end
It was a completely new rear axle, so I wasn't sure what the issue was, finally diagnosed it to the driveshaft, local truck shop could not find anything wrong, but cut it back a bit to redo their ugly second weld (all the others were a work of art, but the shortening seemed to be done completely different) and it's silent now, so something was wrong
Unfortunately, the salesman was ridiculously defensive and miserable even after he reviewed my order for and read back the correct length. So when I retubed it and it fixed the second problem, I chalked the bad tube up to karma and won't go back to them.
A couple buddies used Denny's Driveshaft, then there is Inland Empire, saw nice ones in pictures, but that's about all I have other than cold calling