Big boys are often quoted as being the world's largest steam locos; it's a fact that they are the only 4-8-8-4s ever built, but they are not (a) the longest, that was a PRR S1 at over 140 ft, (b) the heaviest, that was an Erie 2-8-8-8-2, (c) the highest tractive effort, that was a Virginian XA...