Exact length dipstick for 2005 gmc truck sierra 2500hd 4wd 6.6l turbo diesel?

what is the exact length dipstick for 2005 GMC truck sierra 2500hd 4wd 6.6l turbo diesel? I have a dipstick that I replaced but it is not long enough... this truck as you may know takes much oil than a normal vehicle... around 11 quarts instead of the normal 3 or 4 or whatever... anyway when I realized that the dipstick wasn't going to help me because it was the wrong size i worried that I may have put the wrong amount of oil in so I drained ALL of the oil and did it again and got as close to the 10.5 as I could... but I am still not satisfied because I am worried about hurting the truck without the exact amount of oil in it