Well, I'm sorry to hear of your misfortune. I can't offer any knowledge on the cause and effect personally but I would say $3600 for a head is a raping. With some patience you could wait for a wrecked VX to come up on eBay and buy the whole thing for $4000! Not that that is your only viable solution or anything but I have seen them sell for that. Plus, with all the problems I hear about 3.5's spinning bearings there has to be some accessible heads around for cheap. I would get a second opinion and search the web... a mechanic was going to charge me $375 for just a fuel injector - without labor! I found one from ISUZUPARTS.com for something like $80 - turns out I didn't even need a new injector because all that happened was a clip came undone and the injector lost electrical current. The mechanic said they checked it but obviously they didn't. That's why I say get a second opinion. Good luck, I hope it works out for you!