I don't know of anyone who offers just the seal for these gearboxes. I had the same thing happen on my 84 F150, I ended up replacing it with a remanufactured unit. The last gearbox I bought was from Napa, if I remember correctly it cost around $150... plus the core charge. I wouldn't recommend driving it, there is a good chance you will fry the power steering pump. You might be lucky enough to find a gearbox in your local junkyard. You can get one off any Ford F100-350 pickup 2wd or 4wd or Bronco from 1980 through 1996, I'm not sure what year range but some of the Rangers, B2s, and Explorers also used the same unit.
Last edited by pkupman82; December 21st, 2011 at 10:28 PM.