If I have my dates worked out, Robert McCulloch was building the 2, 4, and 6 cylinder drone engines as well as engines for Reed Prentice (saws) before he started building his own brand of chainsaws. Then...McCulloch - Black & Decker - Shop Vac - Employees - Jen Feng (other than Europe)/Husqvarna (Europe) - Husqvarna world wide.
According to a quick search, 72 In³ / 72 HP...
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Mark
I saw a guy carry one of these from a vintage sled swap in St Germain Wisconsin on Sunday. Wish I had seen it first!