GM makes a product. I used it once. Still had to swap injectors shortly thereafter.
I have a Cali 2003 LB7, and yes it came with EGR, catalytic, vacuum pump, etc. Sucks, but it is what it is.
Smoke at idle is classic sign of impending injector failure. Get your balance rates checked, as mentioned, and get ready.
Lincoln Diesel treated me right. My injector bodies were fine, so they refitted them with the updated nozzles. That was I wanna say 5 years ago …. I was concerned at the time, but it turns out to be the right call for me. I monitor balance rates myself, and so far, I’m good.
If you’re handy, injectors can be done DIY. It's a big job, but not particularly technical. Just a lot of labor that I'd rather do myself than pay for at shop rates.
Ran me about $1600 in parts from Lincoln. Probably another couple hundred bucks in incidentals and miscellaneous, and the job took me a long weekend plus (I believe shop time is estimated at 30 hours if memory serves), with me taking my sweet time and taking lots of pics before I disassembled.
The EGR and smog stuff REALLY adds a chore to the job if you have that.
No matter who does it, make SURE they replace the hard fuel lines.
Finally, I am a believer in secondary filtration and water separation. I run an Airdog and a Nicktane before the OEM filter, and have for many years. Cheap insurance.
Good luck, and check out dieselplace.com for a very detailed DIY with pictures. That's what I used.
If/when mine go again, nobody but me is going into my motor.