read:
Toyota Steering Box Swap For 1948-1960 Trucks .: Articles
4x4 shops and rock crawling clubs are good local sources. also you can do a search here:
Car-Part.com--Used Auto Parts Market scroll the search results for the lowest price, you should be able to find several in the 100.00 range. The boxes are practically bulletproof so don't be afraid of a used box.