The 2006 seats use the later occupancy sensor which does not have an additional 'box' under the seat, in line with the sensor wire that goes from the yellow plug into the seat cushion. The 2003 will have the earlier setup, and the two types are not compatible. Changing the sensor pad is not an easy task.
If you do swap seats, make sure you disconnect the battery, and don't reconnect it until the new seats are installed and wired correctly - otherwise you will likely trigger the airbag light and need to have it reset.
Check the length on the seat tensioners, from the attachment bolt to the end of the belt receptacle. If one (or both) have fired, they will be significantly shorter than the ones you have on the car now. If fired, it needs to be replaced - not only a safety issue but this will also trigger your airbag warning light.
You can change the pre-tensioners over from your previous seats, it's just a single bolt holding them on. If you do, make sure you tell the purchaser about them if you sell the old seats on. Cost is about 80 dollars each from online sources like Tischer for new ones, if I recall correctly.
Last edited by WestCDA; 04-14-2013 at 12:59 PM.