The stock shift knob on the GT is not threaded or glued. It has a "D-ring and clip" configeration. Took mine off in just a few minutes--wrap the knob in a towel, place a cresent wrench under the ball, tap firmly but gently with a hammer on the wrench which forces the knob upwards--the knob should "pop off" without damage to it or the shifter rod--MINE DID! 
This is much easier than installing lowering springs [:0]
[xx(]
[B)] on your GT and you will be MUCH HAPPIER
with the end results!
[8D] [?]