(ET) Replacing Front Mower Deck Caster

[john rieffel <rieffelj union edu>]

One of the front caster brackets of the front-mount mower deck on my
E-15 is damaged - the seam which joins the tubular section to the
bracket itself has come partially unwelded.

I have a second deck with intact casters and brackets, and I was
thinking I could just move the bracket assembly between mower decks.
In a sense this looks easy, but naturally 30 years of grass clippings
have rusted all of the bolts beyond hope.  Attempts at using an impact
driver on the bolt head and vice grips on the nut risk stripping the
nut.   What's my best bet for removing these bolts -- chiseling and
breaking them?  Drilling the heads off?  Heating up the bolts and
trying to turn the nuts?

Regards,
jr