The fifth character of the VIN is the engine displacement for the original engine. Your engine is probably a 440, but it could be a 383. The 440 will have a raised, machined pad parallel to the floor, to the right of the distributor as you're looking at the engine. The 383 pad is to the right of the distributor, also, but is at an angle. Either way, the displacement will be stamped on that pad. Here's your possibilities: 361, 383, 400 if a "B" engine; 413, 426 Wedge, or 440 if an "RB" engine. If the engine displacement matches the VIN character, you can check the passenger's side of the block on a machined pad above the oil pan rail to see if this is the original block; the last eight digits of the VIN will be stamped there.
