Italessi....your 4BT, does it have the counterbalance shaft? When I was looking at possible diesels for my K5, there was a good deal on a used 4BT out of a bread truck. (later decided on 6.2) I called Cummins and the rep told me that many of these bread truck 4BTs were supplied without a counterbalance shaft and have a lot of vibration. I happened to talk to a driver also, and he said the alternator bracket on his 4BT step van regularly broke off. What is your experience?