Try posting your question in Recording Gear and Equipment [BG]:
http://www.talkbass.com/forum/forumd...sprune=-1&f=43
The strings on your T-Bird are likely flat-wounds (the outer wrap is made of flat steel wire, similar to the string type used on double basses) or ground-wound (essentially round-wound strings whose outer wrap is made of round steel wire ground flat on its exterior surface).
The strings on your Jag are likely round-wounds (the outer wrap is made of round steel wire, similar to how bass strings for pianos are made).