Uli, are you referring to the differences visible between the 2 fuel taps shown ? i am not sure what differences you are referring to.
i don't think you are asking if there appears a visible difference in the
length of the neck of either fuel tap ?
the only oem replacement taps i have seen produced by Honda are the long necks. and i have noted there are subtle differences between these taps manufactured in the various decades of their manufacture. is it these differences you are asking if "earlier or later" ?
if so, i do not know the differences in taps manufactured during the different decades of manufacture. i do have a few long neck taps at my shop that i believe are probably original period first manufacture, but i have not looked at them closely to the newly manufactured oem Honda taps currently available.
for what it might be worth, the actual website shows the differences between short and long neck taps -
http://cb750sandcastonly.com/support12.htm#Fuel The differences in neck length are obvious. pics of the loose taps were submitted by Al Landry over 10 years ago. the pictures of the taps on blue and green tanks are 4363 and 232 respectively. i am not aware the factory produced replacement parts short necked taps.