As stated by others, lift pump and VP-44 injection pump are weak points. Many improvements have been made here over the years for replacements. 01 and 02 should be new enough to not be a 53 block which had a problem with cracking on the water jackets. Engine is built solid. Need clean air into the motor as they were a little susceptible to upper end problems. As long as these are understood, these motors /can/will pull for a long long time. Nothing like a good diesel setup for running on the road. Peak torque is right where you are driving!!