Depends on how old the pump is...when the last time it was gone through. When low sulfer fuel came about, there was a rash of fuel leaks at the throttle shaft...like you have. When ULSD came about, a few more leaks surfaced, but not a whole bunch of them. If the truck has been sitting a while, the o-ring could just need to be re lubed by use. If not, it will need replaced. Not a big deal, no adjustments will be chnged if you do it yourself. Only needs a front cover gasket, a new tamper proof bolt...it there is one, and an o-ring.