beg to differ ? They are all correct. you have to note JDM VS USDM had subtle variations that i didnt list for instance the Second GSR Type R cast is foundon the B18C3 and B18C4 which are the 4dr gsr and Euorpean GSR. The B16 is the most versitle basicly a run of the mill type r head cast. These are just some of the more popular casts, i know i left alot out.