Originally Posted by Cheapskate
My Centurion's SR stem has a couple of markings. I see "5355-logo-H-76" and below that in bigger font "AX-80". I don't know which one is the date code, the 76 or the 80. The back of the Weinmann centerpull brake calipers has "1234567890ND" in a circle and has the code I-78 in the middle. The DiaCompe brake levers, which btw, did not have any "suicide" extensions, did not have any date codes. By the date of the brake calipers, the bike seems to have been made in 1978 or later, and no earlier than 1976. The seat post diameter is 27.0mm or something close to that.
The stem is form Aug. 1976. The calipers are from 1978. The circle is the month indicator and the "I" is the pointer to the month. So the crank's 1977 code is in sync with the others. If the calipers are from early 1978, then it's probably a 1978 model. If they are from late in the year, it's probably a 1979 model.
The seat post diameter points to one of the CrMo, butted tubesets. It would appear that you have one of the better models.