I'm replacing the fuel pump in my 2001 Chevy S10. 4.3L. The parts store only sell it as a set with the outer shell included, so you just take the old one out and drop the new in, but it's really expensive. Looking online I was able to find places where you can buy just the fuel pump. I know it would be more labor, but besides that is there any real difference in buying the whole thing rather than just the fuel pump? Wouldn't it make sense to replace just the fuel pump and not have to buy the whole thing? Thanks.