Originally Posted by repechage

I will discard the very early cranks and the 151 BCD units. plenty of stuff there that is interesting but not relevant.

As noted earlier, Nuovo Record was a bottom up name used by bike shops to streamline the explanation of the Group.

ok, Pre CPSC will have NO date marks or a numeral in a diamond 5 or under.
Gets tricky with 6 in a diamond, the transition year.
the Pre cranks will have a bigger, "ant hill" at the bore. the Post CPSC will be much lower.
if original chainrings, there will be a pin to positioned behind the crank arm to prevent a chain jam. earlier cranks with the chainring pin will need to be filed back to clear.

what was really going on?
the post CPSC spindle is longer, about 115mm but the broach at the bore was moved, providing the extra space between the chainring and the back of the arm to provide room for the formed lip of the revised cage.

the Q factor of the earlier cranks is narrower compared to the later.

to add to the hot mess, not all 115mm spindles have the same dimensions to the tapers. Shield logo... beware.

then there is Super Record... but that would be telling.