69 XR7 Power Brake Booster Removal

Looking for advice on removing power booster from '69 XR7 convertible. Have removed brake lines from master cylinder, linkage from brake pedal, 4 nuts from studs coming through firewall and bolt from engine compartment. Booster bracket will open about 1/8" at top but will not break free from firewall. Master cylinder is not hitting shock tower, or any other obstacle. Still seems to be attached to firewall, although all visible nuts / bolt have been removed. Have used ratchet strap attached to A/C bracket with significant pull, but still will not come off firewall. Has anyone experienced similar difficulties? Any ideas?

[deleted my post because I was wrong…]

This probably is the hidden 5th nut on the stud that also attaches the bracket to the dash. One of the studs (lower right if I recall) has two nuts. One under the dash bracket, one on top. This has been a bane of many.

There is a double nut on the lower PS stud, you have to remove the dash bracket to see it.

There’s a 5th nuts, thanks to the advice on this board, the hidden 5th was easy to find. Its the bracket that attaches to the lower dash

Thanks for the targeted responses. I will look for the 2nd nut on the stud!