That "canister looking thing: ...look at the starter on the D-30 in post 13414 and the mystery of the canister will be explained.
The 1-40 and 1-50 were modified from the center pull starters but that starter housing remained, later saws had the more conventional top and that starter housing disappeared.
Starting with the 1-41/51 the oil tank was in that same approximate location as the "canister" but looked much different. The D-30/36, 1-40, and 1-50 all had no separate oil tank, bar lubrication was "crankcase residue and heavy condensate" that was channeled to the bar that required running a 10:1 mix ratio. When that proved unsuccessful they made a conversion kit with a divider that placed the oil tank in front of the fuel tank with a manual pump. Better than the "Lubri-Mac" system but still not very convenient.
This is a 1-40 with the oil tank conversion on the front of the fuel tank. There was an aluminum divider plate that went between the fuel tank and the new front cover to create separate fuel and oil tanks.
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This is a 1-42 with the oil tank in the same approximate location as the "canister", notice how McCulloch was using up those modified front covers as the front of the fuel tank on these saws. Waste not, want not.
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Mark