Can anyone tell me the difference between the early/late choices of distibutor caps for my 1976 450SLC? The selection is based on engine serial number and mine appears to have a factory replacement block (no serial number.) At least, I can't find anything stamped on the L/R side of the enigne block.<br> <br> The electrodes in my dist. cap are wearing at the very bottom edge of the metal. That makes me suspect that the correct cap will have longer contacts or sit a bit lower on the distributor assembly.