Hello everybody. I worked at the transmission plant and seen most of the marks. The colors usually were shift color ,blue=dayshift,red=2nd ,green=midnight. The numbers on the tail look like count numbers taken at the end of the shift. The stamping on tail is a final test stamp. The tester maybe had a toolmaker make him the design. The other marks were usually o.k. inspection marks .The speedo marks could be i.d. for gear or production dept.shift i.d. Hope that helps.