FORD 2001 F-550 v.2 - Manual (Page 143)

Do not park your vehicle in Neutral, it may move unexpectedly
and injure someone. Use 1 (First) gear and set the parking brake
fully.
Reverse
Make sure that your vehicle is at a complete stop before you shift into R
(Reverse). Failure to do so may damage the transmission.
Put the gearshift lever in N (Neutral) and wait at least three seconds
before shifting into R (Reverse).
With the 5–speed transmission you
can shift into R (Reverse) only by
moving the gearshift lever from left
of 3 (Third) and 4 (Fourth) gears
before you shift into R (Reverse).
This is a special lockout feature that
protects you from accidentally
shifting into R (Reverse) when you
downshift from
D
(Overdrive).
With the 6–speed transmission you
can shift into R (Reverse) by
moving the gearshift to the extreme
left from N (Neutral).
1 3
2 4 R
D
R 1
L
3
4 2
D
Driving
143