I cut them out of the '85 and the '83 that I got my engine and transmission (respectively) out of. Easy enough to take a small piece of angle and weld a lap joint so you can remove and replace when needed. You can use Rivnuts of simply weld nuts to the existing core support so you can bolt the top bar back in place. Making that piece removable makes service in that area MUCH simpler and, of course, aids in engine removal. I've done several including the one in Mutt the Race Truck.

Remember that if you lack welding gear you can take the top bar to someone and have the lap joint welded in place for you. A tip - most muffler shops can do light-duty welding like this for cheap. It's possible to fish the nuts in when you reinstall the top bar but it's simpler if the nuts are held in place with a tack weld. Also, you can check with a local sheet metal shop and see if they have a Rivnut tool - that works, too.

Dan