1972 Ski-Doo Shop Manual, Page 59Get this manual
1-09-10 DRIVEN PULLEY
18Check gear box oil level using rigid wire as dipstickOil level in 440 models should be 2-14 inches on dipstickOn 640 models, oil level should be 3-14 inches (fig1:.9-32)Replenish, if required with Ski-Doo chain case oilInstall inspection cover and vent plug