5.7 hemi crankshaft, casting and other markings

Anyone know the differences between 5.7 hemi cranks casting #s, year thing or what? Talking pre eagle motors.

Also I noticed there are a's and b's printed on them. I've had some basically new 5.7 eagle motors and you can see when they have a B stamped on the bearing... I assume this is for size, correct? I never measured to see if there is a difference.

Honestly I thought the letters were more to do with source than anything else.