You can use the stock tank with no fitment issues at all. Some have used the stock pump to run a V8, all depends on what year of truck you have and what you are doing with the engine. Example a EFI truck and a carb engine, you will need to put a return regulator in to not flood to the carb due to excessive pressure. Bronco II tanks have been installed in rangers as well a fuel cells but not required.
Matt