i agree with WADS56. You can get close to the same gas mileage with a carb depending on the jetting, and can last a few years before requiring a rebuild. You can also tune them to have the same power as a fuel injected car. They're also fairly easy to adjust, and if the car came with a carburetor it would be ALOT easier to stay carbureted because with FI you'd need to change out the fuel lines (i think), sender in the tank, get and install the wiring harness with all the sensors, not only that but lower and upper intake manifolds, throttle body (cost similar to a carburetor, but only serve 1/2 the function of one), fuel rail, fuel injectors, fuel pump, etc. etc. all adds up very quickly and many of these parts cost ALOT more than the carbureted mechanical or simpler versions. My '84 gets almost 17mpg city, so i have no qualms with carburetors.
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previous name: 84stangLX
'84 Mustang 5.0 LX
my LX
'89 Mustang GT
my GT