The difference in Job Number is a major difference in the truck in some way. In past years, it was only for the change in emissions tuning or hardware near the end of the calendar year. For 2008 you can read it yourself.
Right now, since about January, 2008, we have been under Job 3 of the 2008 model year. To see the changes in Job 3, download the current order guide from
Sunrise Ford Fleet, 16005 Valley Blvd, Fontana, Ca, 92335.
From about July until the Christmas/New Year holiday break in 2007, we were under Job 2 of the 2008 model year. To see what was included in Job 1 trucks, and what changed for Job 2 trucks, click on the following link and skip down to about page 11 and start reading until you finish about page 32. (Those are document page numbers, not the page numbers Adobe Reader says you are looking at.)
https://www.fleet.ford.com/truckBBAS...atsnew2008.pdf ... Basically, they added some options for Job 2 that weren't available for Job 1. (That is a 2mb PDF file, so it will take awhile to download if you are on dialup.)
From the beginning of production of the 2008 models in January 2007 until the July 4th summer break in 2007, the trucks were all Job 1 trucks.