..Im doing my HG's in my driveway. My cpu hard-drive failed, but when i get it working i'll post all the pics that I took from start till where im at now. Im doing EGR Delete, updated dummy plugs, updated HPOP, ARP's, OEM HG's, new up-pipe, coolant filter, 175 injectors w/ stock nozzles through warren diesel, 6.4 banjo's, OEM oil cooler and put X3 tuner, taking heads to machine shop...Now here's my issue, I bought this truck(06 lariat powerstroke 50k mi) 3 months ago and relized the owner before me was a turd and didnt take care of it hence the reason im doing all this. The guy was in an accident with truck within the first year he owned it. Now i have no clue what was fixed or replaced being anything motor or just body work or both. Today i got the oasis report from ford and it said the truck was never in their shop for anything. Leaving the possability the truck could have went somewhere else through his insurance. According to my FICM the truck was built before July 11 meaning it would be 18mm. But with the accident i dont know if the place that worked on it swap the motor or what they could have done. The stickers on the heads are 100% un-readable and the only number i could get is the Head casing numbers wich are the same 1843080C4. I've google searched this a hundred different ways and certain sites say later build and other sites say ealier build. So what im asking is if somebody could help me find out what HG size i need for sure from the head casing number. Any input is appreciated.