Tranny ID help needed

Chrysler used what they called a 10,000 day calender for build dates. In 1974 the number on 1/1/1974 was 5620. So you take your number, 5741 and subtract 5620 and you get 121. That means your trans was built on the 121 day of 1974. 5-1-1974. I have a chart that shows what the number is on the first day of the year. If I remember correctly this started in 1961. Hope this helps you understand.