I sure hope they start including it again. I've only replaced one... the original when I hit 15,000 miles on my '01. Since i had never replaced one before, I asumed that I had the right replacement filter. Well, I took the old one out, and guess what... I had the older style filter. OK, I decide to put the old one back in so I can head to the store and the O-ring was swelled and I couldn't get it back in for the life of me. Everytime I started to get it tight enough, it would sneak out from between the filter housing and the lid. After the third attempt, the O-ring ripped.
Since I had no choice (my wife just left for work), I called my Chevy owning father-in-law and asked him to drive me to the store. The Cummins shop is about 40 minutes away so I felt bad having him drive me there in such short notice. I ended up going to the stealer... Well, $49 later!!!!!! I had a $15 Fleetguard filter. After the first time around, I sure do like the idea of a nice tight new o-ring.