Donato really knows his stuff. According to him the Viper Truck T56 uses 9310 alloy, which happens to be the same material that Gforce uses to manufacture their custom gears, and is NOT the same material that it is used on the T56 that comes in the Viper.
Also the truck gear's tooth are thicker and have a different pitch angle.
The GTS uses a two piece cluster shaft, that he replaces with the one piece cluster shaft, he also heat treats the new components, and shot pinns (sp?)them. He can also give you the .80/62 5th and 6th ratios.
He will replace all bearings, and use some custom lining on the synchros. The fitting he isntalls is to hook up a re-circulating pump so that the oil is put back into the trany right where the input shaft gear mesh with the cluster shaft gear, or so I understood when I talked to him.
I've talked to a few members that have his trany, and nobody has broken one yet, including DC Performance behind their TT set ups.. Over at the V.A one member has SC + juice SRt Truck that he drag races with over 1000 rwhp, and has had zero issues with the Donato Trany. Keep in mind that is a 5000 lb. truck.
As an added Bonus his trany is a lot cheaper than G-force.