No. In fact, there are 318s, 340s and 360s that all use the same casting number rods. The only difference is that the 340 rods are bushed for floating pins. All small block rods are virtually the same, except the early 318 and the 273 rods. They were the same length of course, but much smaller and lighter. They were also bushed. Some people prefer them for a lighter reciprocating assembly. I have two sets myself I am just sitting on really for no reason. I'll probably never use them. lol
