2001 Dodge cummins 5.9

My '04.5 now has over 180k. Only the water pump has been replace on engine. Trans was rebuilt at 154K as first gear was begining to slip. My steering is a rack and pinion and still tight. And my oem lift pump is still going strong at almost 11 1/2 years old. We traveled 7K miles last year to out west and back in 7 weeks without a problem. I have my trans serviced every 30K. Hooking up in morning for a short weekend trip.

Have you checked your owners' manual for the recommend service interval on your transmission when used in heavy service? I'd go by that rather then the consensus of a forum.
I would bet that it says to service the trans every 25,00 or maybe 30,000 miles when used for towing like you are doing.
It's time to get the trans serviced.

If you do not have them you should get a set of gauges. Monitor fuel pressure, Transmission temperature, and exhaust gas temperature (for the turbo). Your truck will run with a bad lift pump, but it will eventually kill the injection pump. Boost is also nice to monitor.
I went thru several lift pumps before I bought a Raptor fuel pump, it is an electric gear driven pump. Second generation Dodges (98-02) had problems with lift pumps. They went from motor mounted to in tank mounted and this seemed to help later models.
I also use two stroke motor oil added to my fuel at a 200:1 mixture. This helps keep the injection pump lubricated and quiets the pump and injector noise some. Some may argue this point , but I think it helps.
Make sure you follow the recommended fluid change intervals in your manual.

can't stress enough what others have said about fuel PSI gauge.

Check your front wheel bearings (Unit bearings ), jack axle up till wheel just leaves ground, then get a pry bar between ground and tire jump and wiggle the pry bar, check for any clunking, spin the tire and listen for any roughness or growling.

Check between rad and AC condenser (use a flashlight) for a build up of oily dirty crust that can block more than 1/2 the rad fines is very typical of 98 to 2002 trucks.

Good luck and have fun on your trip.

My 01 had a fuel pressure gauge installed when I got it (only a month ago). The gauge reads about 11 psi idling and 8 or so when I'm pulling up a hill or accelerating. I know nothing about a diesel but from what I've read this seems a little low. Can one of you experts tell me if this is a problem? Can I increase the fuel pressure?

Hi all... Thanks to all that commented on my diesel questions. Jim2007