Information provided by Paul Bell
It should be noted that those serial number charts should be used as a guide to the serial number range of a "series", and the years the series was produced, but are not necessarly factual for a given model. Example: the model 800 was not produced from 1974 to 1980, it was only in production for about a year, beginning in the last quarter of 1974, but the series was in production from 1974 into 1980. Another example is the 169. It was not produced from 1971 to 1974, all 4006 of them were built in the last couple of months of the series production, in 1974.
So, the charts are very useful as a general guide to the series/model/year of a Cub Cadet, and would be a useful addition to the data base, but there are some discrepancies that could mislead someone, specially someone new to Cub Cadets.