Look into the "metal spray" process, where powdered metal is bonded to the surface after heating it with an acetylene flame. It was once used to repair worn crankshaft journals, so it should be plenty strong to build up the driveshaft. I've seen the system components and metalizing powder on Ebay on occasion. Once the surface is built up, it should be a simple procedure to turn the shaft back down to size, or use a tool post grinder to get a smooth, accurate diameter. If you don't get a hit closer to home, drop me a private message. "The difficult gets done at once- - - -the impossible just takes longer and costs more!" I've been living by that principle for the 60+ years I've been in the automotive business- - - -so far!
www.ebay.com/itm/394655260502?Jerry
