Lots of pixels have been unnecessarily disturbed on the internet for many reasons, this being one of them!
Since you did not post the URL's you mention, I have no idea what you read, HOWEVER:
I started telling customers about the Rochester identification GUIDE some 35 plus years ago, but it is just that, a GUIDE. And I have always told those who listened that it was just a guide. Probably 95 percent of the time, the GUIDE would be correct (which means 5 percent of the time it is wrong!).
Some examples:
(1) 4th digit same as production year - wrong! The 4th digit is GENERALLY the same as the production year carb went in service.
7028273 - production year 1968 - FIRST production year was 1968, but held over through 1969
Also, certain carbs were designated "service replacement units", thus they could be built long after the production year. In the "numbers-matching" world, service dated carbs generally are valued at less than 1/2 of original dated carbs. Also, with a few exceptions (generally those produced in 1969), the service dated carbs will not have "picking" codes.
(2) last digit odd is manual transmission - not always.
7028235 - odd last digit, Carb was original on a 1968 Cadillac El Dorado (when was the last time you saw a '68 Eldo with a manual transmission?????)
(3) date code was in the format jjjy (3 digits Julian date, 1 digit last digit of year) - YES, beginning on some (not all) models in 1968. Prior to 1969, the date code was 2 character in the format "my" where the "m" was a letter representing month (A=January, B=February), etc; and the "y" was the last digit in the year; HOWEVER: in some years the "I" was used, so "L" would represent December, and in other years, the "I" was not used, meaning "M" would represent December
(4) There are other discrepencies, but these should be sufficient to prove the GUIDE is NOT 100 percent.
Use it as a GUIDE, and it can serve you well, but if you have to be certain, look up the exact number.
Jon.
