Ford 2006 F-350 Owner's Manual page 156

Tires, Wheels and Loading
Towing a trailer places an additional load on your vehicle's engine,
transmission, axle, brakes, tires and suspension. Inspect these
components carefully prior to and after any towing operation. Refer to
Transmission temperature gauge in the Instrument Cluster chapter
for the transmission fluid temperature information.
The following trailer towing charts apply to vehicles equipped with
gasoline engines; for vehicles equipped with diesel engines, refer to your
6.0 Liter Power Stroke Direct Injection Turbo Diesel Owner's Guide
Supplement.
Note: Do not exceed the GCWR listed for your vehicle on the following
chart/table, or the GVWR, GAWR or tire ratings specified on the Tire
Label or Safety Compliance Certification Label.
Towing trailers beyond the maximum recommended trailer
weight which exceeds the limit of the vehicle's GCWR, GVWR,
GAWR or tire ratings could result in engine damage, transmission
damage, structural damage, loss of vehicle control, vehicle rollover and
personal injury.
Maximum GCWR - lb. (kg.)
Engine Rear axle ratio
F–250/F–350 Single Rear Wheel (SRW)
5.4L
6.8L (F-250)
6.8L (F-350)
F–350 Dual Rear Wheel (DRW)
5.4L
6.8L
6.8L 4.88/5.38
156
2006 F-250/350/450/550 (f23)
Owners Guide (post-2002-fmt)
USA (fus)
Manual
transmission
3.73 15000 (6804)
4.10 17000 (7711)
4.10 20000 (9072)
4.30 22000 (9979)
4.10 20000 (9072)
4.30 22000 (9979)
3.73 15000 (6804)
4.10 17500 (7938)
4.10 20500 (9299)
4.30 22500 (10206)
F–450/F–550
26000 (11793)
Automatic
transmission
16000 (7257)
18000 (8165)
21000 (9525)
22500 (10206)
21000 (9525)
23000 (10433)
16500 (7484)
18500 (8391)
21500 (9752)
23000 (10433)
26000 (11793)