This is more of a suspension question, but if you are talking about the upper control arm bushings that are sitting on the axle, then you have to press them out. You can buy a bushing press from Maximum Motorsports for just the thing. It's cheap and effective. Here is the link.
Go to autozone and see if they can rent some kind of tool like that. Or take it to the shop and pay the same money you would for the tool for the labor.
ReplicaR, i came on here to ask the EXACT same question... we dropped the upper arms this evening and found out they were in the axle and not in the arm >.<
thanks for the link and the info!
-Chris
P.S. - if i hadn't already promised Paul my first daughter in a different thread, id defiantly send her to you!... thanks again!
modify:
heres the same tool on stang suspension . com, except if you use our forum discount they knock off $1.50...... mine came to $38.00 after tax, shipping, and discount...