[north]

What’s interesting is in that era there were 4 different levels of antenna retraction from Pontiac. The worst was The 69 Firebird that leaves probably 8” or so out when retracted despite using a unique shorter antenna mast (thanks to a really shallow trunk). The 68-69 A-body (It uses the same mast as the big cars) also did not fully retract leaving a few inches up. Next the 68-69 big cars, the mast would fully retract into the bezel and nut which stood proud of the body an inch or so. Last was the 68 GP, it had a unique bezel that was body colored and flush to the body and the mast fully retracted into it.

The 68 GP power antenna offset its retraction championship by having a major design error, the trunk lid had a trapezoidal trunklid with the bumper end being wider than the forward end. So when the antenna was up the edge of the trunk lid would rub as you opened it and you’d have to push it away to get the lip clear. Worse, if the antenna was up in the typical half way (30 odd inches) and you tried to close the trunk you’d catch the top of the antenna with the lid and mangle the mast!

[Cammer-6]

IIRC the fix for the GP was shim the antenna body so its slightly tilted out when fully extended. Doesnt take much.
So the bottom of the antenna body would move inward slightly placing the fully extended antenna outward.

Originally Posted by north

What’s interesting is in that era there were 4 different levels of antenna retraction from Pontiac. The worst was The 69 Firebird that leaves probably 8” or so out when retracted despite using a unique shorter antenna mast (thanks to a really shallow trunk). The 68-69 A-body (It uses the same mast as the big cars) also did not fully retract leaving a few inches up. Next the 68-69 big cars, the mast would fully retract into the bezel and nut which stood proud of the body an inch or so. Last was the 68 GP, it had a unique bezel that was body colored and flush to the body and the mast fully retracted into it.

The 68 GP power antenna offset its retraction championship by having a major design error, the trunk lid had a trapezoidal trunklid with the bumper end being wider than the forward end. So when the antenna was up the edge of the trunk lid would rub as you opened it and you’d have to push it away to get the lip clear. Worse, if the antenna was up in the typical half way (30 odd inches) and you tried to close the trunk you’d catch the top of the antenna with the lid and mangle the mast!