If you want to stay with the torque tube setup, it looks like you're going to need a different housing. Even if the hole can be brazed up from the outside, I don't think I'd trust the integrity of the machining any more. This would be a good time to convert to a later model housing with the open driveline, and a corresponding transmission. The 55-59 3.90 ratio center section with the open driveshaft will bolt into your existing banjo housing, but you'll need to figure out a way to make the pivoting spring mounts rigid if you do that. Welding those rubber bushing pivots is a real PITA!
Jerry
