Rugby 3,
First, after repeated attempts to fix your original trans. its time you demand a new one!
If all eles fails, go to
www.car-part.com . I just checked and two trans. that will fit a 1997 v8 4x4 F-150 standard trans. showed up in your home state of N.H. price was $750 and $950 !!!!!
If your willing to drive out of state or pay shipping, you would be able to find the newest manual trans. possible for your application.
I used the site to find a 2002 auto trans. and converter with 2000 miles on it for our 1999 Firebird for a total price of $600 buck!
Good Luck!