Mitsubishi Triton 2012: Head assembly replacement

You don’t tell us why your ute needs a new head at just 134,000 km, so it’s hard to comment. If nothing untoward has happened to cause the problem, like overheating, then you could try and convince Mitsubishi to cover the cost of repairs, but unless you have a full history that clearly points to a manufacturing fault I think you would struggle to justify a claim.