Exactly! My reference to a 30 year old truck was from an article done in the connections magazine you see at truck stop's. Seem's there was a fellow who liked the astetics of 70's era kenworths. Custom paint and lot's of chrome made it a beautiful truck. He had gone through several motor's and transmission's, changing them before he ran into service failure problem's. Now...not to beat a dead horse,but, i seem to recall that the major selling point of the T-300 was listed right on kenworth's literature stating the bigger motor and tranny were qualifier's for class 8 distinction, much as international's 7400 model makes the same claim, as does sterling's 960. Apparently the bigger motor and tranny and differential, reinforced frame work and sturdier suspention, and bigger brakes on a smaller, lower chassis were designed to give you the million mile durability with a cheaper and easier to handle vehicle. Now the cat 3126,(as well as the MBE900 which is'nt mercedes at all, but rather a barely modified detroit deisel series 60 built at the allison engine plant just outside of detroit), are both industry rated at B50, which means; at least 50% of these motors have made it to 500,000 miles without needing any major work. Take that for what it's worth. My point being, i think that, such as the case with the T-300 up at the top here, should'nt necesarily be considered class "7" out of hand.