If you have tranny shifting problems associated with a non-functional speedo, 99.5% of the time it will be the governor gear melting or stripping.
I don't know if this will be in the FAQ, but it should. The governors are nowhere to be found new, and even tough to find used. Luckily, the governor gear is a plastic piece that can easily be replaced. The service gears are not commonly available, but I have found a source here in Providence, where they have perhaps 350 left @ $5.00 each. This really is something that Fusick's should buy a quantity of, just so this tranny shop doesn't mistakenly throw out this stash.
Back to the topic, the governor is held down by one bolt, and can be removed with some wiggling after you disconnect the speedo cable and its gear from the tranny. The gear will probably be trashed.
Hope that it's the governor gear! Cheap and easy fix; other causes might not be so nice!