Not to take anything away from the truck, and sounds like you got a fair price. On the Carpet, Ford didn't fully carpet under the seat and all the way to the tank. And that tank is a reproduction like the one at the following link:
http://dennis-carpenter.com/gas-or-fuel ... TZ-9002-A/
In '70, I believe the original tank would have been black as well. Never silver.
Condensation at probably settled in the old tank and rusted out. Replacements are cheaper than fixing originals, so it was replaced. Certainly doesn't take away from the overall package, so don't let it dissapoint ya!
I hope you
drive this beauty, she sure does look good.
- Joseph