Oh, and batteries lasted maybe 2-3 years.
My '77 Wagoneer is holding up pretty good, not much plastic but still it's showing it's age. You are right, the heat really kills a battery.
So back in 1979 I bought a JC Penny 'Lifetime Battery' "It's the last battery your car will ever need"
They were right! I haven't bought a battery since 1979, when it dies they replace it for free.