i need help..

there is this guy in the place for the swap, telling me i have to replace the fuel tank..
thets what he told me, i asked why.. he said, "supposing your car is a hatchback, we have to replace the gas tank.." after that he said something bout carb.... i dunno what that means, carburated? is there a carburated eg?

by the way.. this is in the philippines...