I just did the same thing on my 67. The bar came off the ball stud, luckily i was in my driveway. Anyway, I bought a new z-bar from NPD and took my ball stud to my local GM dealer to see about a replacement. There computers only went back to the seventies, so he couldn't look it up. But he had on in his inventory for a 1976 firebird. He went and got it for me and it was a exact match! So i would try that at your local GM dealer. Make sure it has the gasket on it that keeps the grease in. Hope it helps.