i have 04 tl base. i'm trying to replace my strut mount. the shock assembly is out of the car. compress the spring, but my strut nut won't come out and the hex screw on top of that is strip rounded. i try impac gun and it still won't brake apart. the strut also spin with the nut even those i use wise script to hold it down . any advice what should i do? do that hex screw need to come out to be able for the strut nut to come out?

 

Grind it off or use a grinder to make notches along the sides and then use lock pliers to twist it off.

 

Air impact gun on high? If so, nothing left to cut it off. Vise grips on the polished rod a no-mo though.

 

if you are tossing the old struts out- who cares!!
but in general Turbo is correct
If you were swapping just springs- no toothed metal tools allowed on the smooth shaft or you will damage the internal seals when rod compresses inside the shock

take it to a shop- they will have more air pressure and bigger guns
Shops often hit the retainer nut with the gun slightly before compressing spring- makes it easy to finish the job
Beware this is as dangerous a thing as you can attempt!!!!!!!!!- potential death or at least an emergency room visit for rib fractures and punctured lung may occur~
should that nut decide to spin all the way off-
I got away with it for years but dont risk it any more