It will be interesting to find out what broke on your trans. Parts do break. There are a bunch of cast parts in a transmission, and factory variation in casting quality is not uncommon. Remember these parts were not designed for that much torque. Let us know what JPT finds.

If it is any consolation, IMO with a brake it is more important to use roller bearings. The thrust washers don't do as good a job and cause wear in that application. Others have mentioned the rear roller support helps life with a brake too.