My opinion is that when the current block (V2.0) was cast and machined there is some swarf inside one of the galleries leading to the Turbo lubrication line.
In "good" conditions this swarf has been bypassing the oil and allowing the Turbo to function correctly.
Every now and again the swarf has then turned/shifted, restricting oil flow and the resulting outcome is the Turbo has eaten itself.
This would explain why the Turbochargers have had varying lifespans / survival rates.
So far, the accumulated costs to LR would have easily replaced the Engine (V3.0) and most likely had Digger well on his way and happy.

