Can you replace just the nut on the pump side of the power steering hose.on a 2007 buick lacrosse 3.6l

No you must replace the complete line unless you go to a hydraulic line repair shop they may be able to rebuild the line with a new nut. You may consider a thread file if its the threads that are damaged. I have had great results with a thread file.

I hope this helps.

Roy

Unfortunately no. If the threads are still functional use channel locks to remedy worn down nut sides.