SPEED PRO Chevy 400 Hypereutectic Dish Top Piston+MOLY Ring Kit use 5.7 rods. Your Choice of over sizes!! (.030" Bore 4.155") Hypereutectic Coated Skirt Pistons with Matching Rings. 5/64" 5/64" 3/16" ring grooves .927" pin diam. 3.750" stroke