Research Note: Later factory serial lists record this run as ending at 31,100. However, earlier lists reveal the original ending serial number was designated as 31,000 with the next run beginning at 31,101. It is likely an attempt was made to correct this discrepancy in later serial lists by extending the previous run by 100 units. However, observations of surviving samples have confirmed that this run terminates at 31,000 and the next run begins at 31,001, despite the inconsistencies in the later factory serial lists. As a result, the total estimated production displayed for the Grade 69 will be inconsistent with other resources that rely on the factory serial lists.