FYI, Toyota makes a cast Iron V8- 4.7L available in the Tundra. They also last year made the industrial package (hardened valves, engine protection system standard on the GM since they had several issues with the standard GM package). I think your on track with the cooperation with GM but its not as good as a Toyota engine. The 4 cylinder GM they used to put in the 6 series-6,000# was proof enough of that.