Whatever you have done is working at 400000 + miles
My only Dmax has issues and smokes, i dose it with ATF once in a while, but i think the issues are deeper as the hoses are always under pressure and needs constant top ups on coolant.
It continues to be ignored by me as it is low on the totem pole.
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews