Before I break something: any tips on body to rear axle brake line connector removal?

I'm all set to mount up my fresh rear axle assembly. I received some good tips from this form (thanks again) on replacing the junction box/brake line connector that mounts on the axle housing (along with the vented bolt). Thanks again for that info. :D

So the original flex line that connects from the body to he rear axle seems to have been on there since my car rolled off of the assembly line in October of 1972...yeah, real safe, I know...

The problem is that the line is supported by a thin sheet metal tab where in connects to the hard line on the body. With wrenches on each side, the fittings just don't want to budge and I'm darned near damaging the body-side line...which I'd really like to avoid...and in the process, it that sheet metal tab looks like it could get bent pretty easily.

I have sprayed the heck out of it with the Pb Baster...but I still think I'm missing something. Is there a clip that runs parallel to that tab that needs to be removed? I can't quite see anything but my lighting isn't great so I'm hesitant to apply any more force without checking. If not, is there any technique that you guys can recommend that would avoid the need to bend up new brake lines?

As always, any suggestions would be greatly appreciated. :D