Thanks Art. I ended up buying a 50' #10 extension cord and the appropriate receptacle and plug. Cut the ends off the extension cord and wired up the receptacle on one end and the plug on the other. Works great and it was significantly less expensive than buying a ready made welder extension cord.
Tom S.
I just built a 10 foot extension cord for my fig welder. I used 10 gauge wire and the 50 amp plug and receptacle. By the time I was done it probably would have been cheaper to buy this: http://www.eastwood.com/welder-extension-cord-25-ft.html
I did learn some things building it.
Al