[eschaider]

You may be better off with a replacement case.

As strictlypersonl pointed out, with section thicknesses like this, disassembly and preheating will be necessary. When the welding process has been completed you run the risk of case distortion that may require re machining. In the long run the replacement route may be both simpler and more psychologically comfortable after you are done.

The upside (if there is one) is that the transmission is not difficult to take apart and put back together and it is a great educational experience that will give you an intimate understanding of how it works.

Ed