I need some help on figuring out what size differential I have. I own an 04 150 ext. cab XLT 5.4 4x4. It came through with the HD payload package, tow package with 3.73 gears. I was told it has the 9.75 rear, then I was told it has the 10.25 rear. The GVWR is 7200 lbs. I am thinking of a gear swap to 4.10's in the future, but do not want to pull anything apart until I know for sure. There is still the tag on the cover. I was wondering if that would give me info on it. The dealer is no help, they told me it had an 8.8. That is totally false info, they never put an 8.8 behind any F-150 with the 5.4. Any help would be great!

 

The HD package comes with 4.10's and LT245/70R17 tires and a Ford/Visteon 10.25" semi-floater with a 7 on 150mm bolt pattern. Also they have an 8200lbs GVWR, only come with the 8' bed and 5.4L unless its a fleet order and then you can get it with the 4.6L. You probably don't have the HD package since you say your GVWR is only 7200lbs, in which case, then, you have a Ford/Visteon 9.75" semi-floater.

Details of the HD package for the 2004 model year:

HEAVY DUTY PAYLOAD PACKAGE (627)
Usage: Increases GVWR to 8200 lbs. for improved
payload and towing
Availability:
• Regular Cab Styleside 8.0’ box (145” WB) or
SuperCab Styleside 8.0’ box (163” WB)
• XL and XLT
• Requires 5.4L V8 Engine
• 35.7 gallon fuel tank required w/Regular and
SuperCab 4x4
Includes:
• 50-State Emissions System (425)
• LT245/70x17D BSW A/S tires (T74)
• High capacity 17” 7-lug steel wheels (64K)
• Heavy Duty shock absorbers, frame and 72 amp
battery
• Upgraded springs, radiator, and auxiliary
transmission oil cooler
• 10.25" gear set with 4.10 axle
• Standard 4.10 axle (Optional 4.10 Limited Slip – XB5)
• Optional Snow Plow Prep (4x4 only) – (63A)

 

you have the 9.75 rear, you also do not have the heavy duty package but rather the standard package.