I would replace the lift pump as well as the injection pump. I also would install a big line kit as it's the perfect time to do it. I always run diesel additive designed to lubricate the IP and LP as insurance.

I would read the instructions carefully when deciding to do the job yourself or not. It's not rocket science, but it can be intimidating. Be very careful if you have a leak on the pressure side of the pump as the pressures can inject diesel into your body (like a water jet cutter) which is bad. That said, I would do it myself and you could also if you are comfortable messing with the fuel systems on your own cars. Priming the system is tough after the change, but patience and following the service manual procedure will get it done. I would not do the job unless I had the FSM handy just in case.

http://www.vulcanperformance.com/category-s/150.htm

http://www.commonwealthdiesel.com/?gclid=CO7dgb2t4aACFRdYbQodOR4ABw

Some info

http://www.dieselbombers.com/24-valve-2nd-gen-dodge-cummins-98-5-02/14859-lift-pump-psi.html

http://forums.dieselpowermag.com/70/7450...mins/index.html

http://www.dieseltruckresource.com/dev/archive/want-cummins-campain-lift-pump-t104570.html

http://dodgeram.org/tech/dsl/ISB/vp44_reliability.html