Is your engine an 8.3 ISC, if so yes, the lift pump is located above the starter.
The lift pump is known to be a problem, in fact Cummins had a service bulletin ( I have a copy of it dated Nov 2006) instructing shops to change the gasket on rigs that come into the shops for other work, they did not have a full blown recall. They then instructed the shops to just change the pumps, initially at no cost to owners. I guess this was getting too expensive so they now let the owners discover the problem and pay for the repair.
I would suggest you join the Cummins Quick Serve site, once registered with Login & Password you can put in the SN of your engine. I will then bring up a new page with tabs at the top including parts and service. Under the parts tab you can see different catagories of the engine including fuel delivery. Look under here for the lift pump, it will provide part numbers etc.
Cummins will not sell the gasket anymore but I did find a source for one, Capital Volvo in Montgomery AL. I ordered a gasket just to have one on hand to get me going, I would then replace the pump itself. The gasket part number I ordered is 4928511, cost was $6.71 + shipping. Initially they wanted to ship FedEx for $$$ but instead the person I talked to said they'd just put in an envelope >> cost was $1 so total cost was $7.71.
I inspect my fuel lift pump everytime I'm under the coach. You should be able to access the pump from your closet engine hatch, not easy to get to or see. A new lift pump is ~$350-400, if you have a shop do it add that much more for labor. My fuel pump PN is 4935005, I have all the info from the Quickserve site saved for future reference.
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi