so here is what i've learned. all gen 1 stuff as well the gte head doesn't look as stout as the ge head. there is more external bracing on the ge head. the fuel injector ports on the gte head are much wider than the ones on the ge head all the valves are the same diameter the ports all appear and measure the same the jdm ge head is not stamped, possibly not made, by yamaha all gte heads are yamaha the usdm (egr) heads have a coolant passge port to the egr system inside the cylinder head the egr runs off the number 4 cylinder only GE head GTE head