Ok, So I have this customer at work. He has a 98 3500 Dually. One day, I was talking about wanting to sell my Burb and buy a diesel, and he chimed in that his was for sale. I asked what it was, and he claimed that he had a "Duramax," I looked outside, and saw his truck and told him that couldnt' be the one he was talking about. He confirmed that it was in fact the one he was trying to sell... I told him that the 98's weren't Duramax. They came with the 6.5, until 00, and then they started with the Duramax for the 01's and up models. He then asked why he had Duramax badges all over his truck, and I replied with "I can slap some badges on my 5.7 and call it a duramax, but its still a Vortec 350" He then brought in a plastic cover from under the hood and told me to read it. Of course it said "6.5L" and I asked what that proved.. He said that was what proved it was infact a 'max. I told him he was wrong, that they were 6.6L. Well, the conversation continued and got pretty heated, a couple of my friends were at my work, listening in the background. They guy swore up and down that I was wrong and he has a Duramax. On his way out, my friend tried telling him the same thing.. He swears we're both wrong.. Soooo. How accurate was I? I don't know too much about the 'maxes, but I thought I knew enough.. Was I wrong?