I'm doing basic maintenance on the truck that I just purchased-
'04 f150 heritage 4x2 5-speed 4.2 64,000 miles.
Tranny fluid was black black black.
Doesn't look like it has been changed before.
I have no problem or grinding when shifting gears on the truck before or after changing the fluid. There were some metal shavings on the drain plug- maybe about the amount you would get if you shredded up a dime- if you can picture that.
I don't know how bad of a sign the black fluid is, nor how long the manual tranny will usually last, so I am looking for opinions.

 

Your truck, according to Ford, was due for a fluid change at 60K. As it is still shifting properly I would leave it alone. My transmissions usually have metal bits on the magnet. Fuzz is normal.

 

I changed it already. Can't tell any difference, but I like knowing it has red fluid in there now.