312 rods are ECZ; 272/292 rods are EBU. The C1AE heavy-duty 292 truck rods are the same length as 312 rods. EBU = 6.324. ECZ & C1 rods = 6.252. The rod journal diameter and piston pin diameter are the same for all Ford Y-blocks.
312 pistons can be used in a 292, but OEM 292 pistons, having longer skirts, can't be used in the longer stroke 312.
ECZ-A, B, C and B9AE blocks can be either 292 or 312. +.060 292 pistons are common and could be confused with + .010 312 pistons. I wasn't sure if my 1956 ECZ-A block was a 292 or 312. I removed a head, measured the bores, and then cleaned carbon deposits off of the tops of two pistons and found .060. I concluded, therefore, that it's a 292. Although there are + .060 312 aftermarket cast pistons available, it's uncommon to go + .060 on a 312. The largest off-the-shelf 312 forged pistons that John Mummert sells is + .040.
Keep in mind that the original 292/312 pistons were .020 below deck height. The factory used shim head gaskets with a compressed thickness of .025, provide a quench of .045. Aftermarket cast pistons could be as much as .035 below deck height. Using a shim gasket would give you quench of .060, which is the outter-most limit to prevent detonation. If you have aftermarket cast pistons and composite gaskets, like Best, which have a compressed thickness of .046, your quench will be .081; this is not acceptable. If using composite gaskets, which will provide a better seal, particularly if your head and block deck surfaces are less than perfect, you'll want to zero-deck the block.
FYI; The heavy-duty 292 truck engine with the shorter 312-length rods compensated for the difference in rod length by using pistons with a taller compression height. I don't think you'll find the pistons off-the-shelf; they would have to be custom forged pistons.
