Hi Patrick,
Sorry, but given the information you've provided nobody is going to be able to help you. Actually I'm not sure what you're really asking.
As far as I know (and I'm willing to stand corrected if wrong) the battery in the trunk detail is likely an owner-made modification and not a factory installed feature. So that won't help you decode or identify anything. You do (presumably) know that one spider is a 1976 version, so that should be your starting point as to figuring out what the car is. I'm not sure what number you're using or what online decoder.
As for the other car, I hope it is one of a similar age. Even though there are parts that can be shared across the years, if you are looking to do straight swaps, you're better off to have the donor and the driver as similar as possible.
--Toronto