Tangerine makes a replacement for the threaded insert section if you need it.
Tangerine - Trailing Arm Threaded Mounting Sleeve"The rear outer suspension consoles each have three of these. Our piece is an accurate repro of the factory component. This sleeve makes a quality repair possible if you are unable to repair the threads after breaking a bolt. A 7/8" hole saw will cut through the top weld on the console making it easy to remove the old sleeve."
It is a backup to a problem that exists.
Also there are plastic plugs at the top of these sleeves. You can add some penetrate. Take a punch and drop it in the top and top the top of the bolt. Rinse and repeat until your ready to give it a try.
I have a set of reverse drill bits to give it a fitting chance.
Best of luck with this repair.