i do not use the small head gaskets you have if the bore is 4.375 and you use a 4.370 the head gaskets ring will sit in the bore that is no good and if the bore has a chamfer on top of the bore this dose not get better so i have use the 1017 fe-pros if you want to blow head gaskets run the small one .the deck pins that hold the gastket can be off you are play with fire