I spoke with a local Ford Thunderbird Mechanic Specialist (everyone here in San Diego goes to him) "Hilltop Fords" (Escondido,CA) . He also mentioned the lifetime lube used in the front suspension, stating that the "lifetime" back then didn't expect to mean 40+ years...
I showed him the zerks on the front upper suspension arm of my bird and he said that was both great and desirable. It meant they had already been replaced and upgraded to the long-term best solution for lubricating the suspension arm. (The old lifetime grease will not last and should be replaced if it hasn't.)
Based on his advice, and that my bird still rolls with 350k+ miles on her, I would recommend if you have the option to go for the zerks, do it.
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