Hey Cowboy, I added an Eliminator style spoiler to the decklid of my 68 where there wasn't one before. At first the spring rods were strong enough to hold the decklid open. But, they quickly became weaker and I needed to do something to help support it. I believe (but don't quote me) that real eliminators had a prop rod from the factory to cure this problem, like those that hold up the hoods on some of the cars that don't have springs on their hinges. Badcatt and I as well as others here went a different route and are using a gas charged "ram" type of device like those used on a hatchback to help hold the decklid up. Hope this helps the explanation a little.
Mark