I own a 1973 Dodge M-300, 440 cu. It runs weaker with the ethanol, but I’m not having problems with the fuel system. My mechanic went through it in May, and it’s clean as a whistle. I use Chevron gas. It’s more expensive, but has a very good stabilizer blended in.
I hope the stabilizer works. I don’t like throwing money away on preventable things.
I hear it attacks the plastics used in the non-auto engines. That they’re not made to withstand alcohol.
I hope your mechanic replaced all the rubber fuel line in that ‘73 Dodge with the newer Gates line that has the green stripe. The older type rubber fuel line will rot and leak, regardless of fuel additives.