FORD 2002 F-550 v.3 - Manual (Page 264)

Do not use supplemental transmission fluid additives, treatments or
cleaning agents. The use of these materials may affect transmission
operation and result in damage to internal transmission components.
Checking and adding manual transmission fluid (if equipped)
1. Clean the filler plug.
2. Remove the filler plug and
inspect the fluid level.
3. Fluid level should be at bottom of
the opening.
4. Add enough fluid through the
filler opening so that the fluid level
is at the bottom of the opening.
5. Install and tighten the fill plug
securely.
Use only fluid that meets Ford specifications. Refer to Lubricant
Specifications in this chapter.
Maintenance and Specifications
264