Before you get too radical, try soaking with penetrating oil for several days. You aren't in a big hurry to fix a daily driver. Use a 3/4" breaker bar after the long soaking. I wouldn't use any extreme heat unless ALL else fails.
Good luck, looks like a good prospect.
Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!