Rusted strut inserts

[DK]

Hi all,
I finally got around doing the front and rear struts on my 4000, but
have run into a major problem - the strut inserts are rusted in pretty
bad. The car lived in Colorado for quite some time, but has no rust
anywhere else. Looks like the previous owner/mechanic did not put any
oil down the strut housing/tube and barely tightened the cap over it.
I had it soak with several oils (liquid wrench, WD40 and other stuff)
over night but no use. I tried turning it with a vice grip, tried
hammering it out, but all no luck.
I am considering putting a torch to it, but don't want to fatigue the
strut housing. Are there any other options for me (besides getting a
new strut housing)

Dave