If your cruise drops out, especially over bumps, I'd be having a look at your brake light switch or a fault in your trailer brake wiring or even globes. Does pressing 'resume' reinstate it or do you have to press the 'on' button again?
Agree the Toyo 4.2l is indestructable and best engine they ever made.
Most modern diesels are serviced every 15000kms now and while not ideal its a selling point I guess. But you don't see them doing 500,000 on original engines thats for sure.
Biggest killer on common rails is water in fuel. Kills the pump and injectors quickly and costs a small fortune to replace.