The tractor is a 1976 B-80 8-speed. If you go to Toro they have incorrectly identified it as a B-60. The wiring is the same as the 1977 models and the wiring diagram for those are in the Files ofhttp://groups.yahoo.com/group/wheelhors ... anuals2_1/
The file is named "Tractor 1977 B-60 B-80 B-100 C-120 C-160 Wiring only"
The operator manual is also there and should be the same.
The 7559 is the serial number and the last 4 digits are the Julian build date. Most likely it should read 6030 which is 30th day of 1976 = Friday January 30, 1976. Another B-80 has a serial # 7465 and a date of 6022.