That rod & clevis sets against a vacuum valve- the part that protrudes out the back. The rod is usually held in place with a circlip in the valve, at least on '71-'75s. The valve may be made of plastic and is fragile. If it gets banged in shipment or while being installed, it will crack internally and you'll get no vacuum boost. It is not simple to change out, either.
Second note- the boss or swelling on the part of the booster that is inside the front trunk and holds the vacuum hose check valve: it can be 'clocked' either to the inside nearer the battery or outside nearer the fender. Most Panteras have the hole in the floor for the vacuum hose closer to the battery. If yours is reassembled wrong, you'll have to plug a hole in the floor, drill a new hole (with grommet) and reroute the big vacuum hose under the front end. The retaining ring can be unbent and shifted to move this but not usually while the booster is in the car.
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