The SDM (airbag module) in a 99+ truck is UNDER the driver's seat bolted to the floor. The only possible airbag wiring would be if the seats had side impact airbags, in which case, you would easily be able to see them. Any airbag wiring will have it's own yellow connector with a locking pin.
Off the top of my head I know that there are two wires for the seatbelt, a host of them for power (heated, adjustment, lumbar) and if they had memory they probably had a class 2 Serial Data wire going to them. Some trucks also had a transmission indicator wire going to them for what reason I have no idea. The 2001 truck I pulled my PWDL wirign harness from did, but my 2002 didn't.