I see some sort of pump or compressor looking thing above the rear axle under the bed of my truck. Does anyone know what it is? Also how do I find out what rear gear set I have from the factory? Are they all 8.8" housings in the 2004 ford 150 fx4 supercrew?:

 

You may have the load-leveling suspension option, which would explain the compressor, and there will be a tag on the differential to indicate what gear set is installed. There may be a tag on the driver's door, as well. Someone else will chime in, I'm sure.

Andy

 

If you have an 04 FX4, it has a 5.4 engine. With that you get a 9.75 rear diff. As far as a compressor, to my knowledge, there was no option for air bags or a load leveling suspension. Pictures might help.

 

Post the axle code from the door jam sticker.

Get a pic posted if you can. I've heard about (never seen) a load leveling suspension option on '97's but not for '04.

Adrianspeeder

 

I'll get a pic soon. Where's the fuel pump on this particular truck? In the tank or on the frame?

 

My Expy has the charcoal/evap cannister in the same place you describe...could be that.

 

In tank. The last year for gasser frame pumps was '89.

Adrianspeeder