Well. Here’s what I have. I’ve got many shafts. I’ve got a 340TA that I was the first person to take it apart. I’ve got multiple 69-70 340 steel shafts, multiple 318-3 truck cranks, multiple 318 cast shafts and even a 73 340 4 speed crank. I label them when I take them apart. They all measure 2.155-2.157. All my flywheels from oem to aftermarket measure 2.158-2.160. Even my 440 stuff falls into these measurements. I’ve had some tight through the years but never like what your describing.