GBR shafts are built by Six States (GBR's "driveline division"). I'm not 100% certain on this but I believe that they have Spicer U-joints. I've run them and had fine luck with them. In fact, I think I might even have a used one to sell. They're not "cheap" and you're dealing with GBR.
Tom Wood's, like GBR, is also Utah-based. They build their own driveshafts (no outsourcing) and can build whatever you want. You call them with the measurements and they build to order and ship direct. I called and had my shafts at my door here in Kansas three days later. Theirs is a very nice product and they are great to work with. They use Spicer 1310 U-joints, which are about as universal as you can get. You can get replacements at any auto parts store. Their dual-cardan shafts include a grease fitting to grease the centering ball.
I have seen both brands fail. The key to driveshaft life is using quality U-joints and maintaining them with frequent lubrication. Buy a magnetic level (or use one of the iPhone apps) and measure the angle of your t-case output flange and your diff pinion flange and provide this to the vendor when you call and they will square you away with the right style.
My personal choice? Tom Wood's. The story behind that is best told with whiskey and a big campfire.