According to the "Standard Catalog of US Military Vehicles," by David Doyle:
The otter had a totally enclosed, insulated aluminum body and space for eight passengers plus the two-man crew, or 3,000 lbs of cargo. There were hatches in the roof, and a pair of doors on the back for loading and unloading passengers or cargo. The crew compartment had doors on each side.
There was a propeller mounted below the pintle hook for use in the water, and the fuel tanks were mounted externally. The location of the fuel tanks and external storage varied during the production run. They were centered on the hull side on early vehicles, and shifted to the rear of the hull sides on later models. All otters had a 5,000 lb capacity winch mounted in the rear compartment under a seat.
The road wheels on the Otter were pneumatic like those on the Scorpion instead of solid rubber like most other tracked vehicles.
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The engine was a radial Aircraft engine that used a electric driven flywheel to get the gas engine turning before actually turning on the ignition. Sorta whined like the old hand spun flywheels on the older aircraft.
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The Otter uses the Continental AIO-268 air cooled,injected,opposed 4 cylinder engine.The engine and transmission can be changed out in about 1 hour.Everything is quick disconnect fittings and the transaxle has a half-clamp that pivots out of the way.
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Almost every part on the otter was purpose made for it including the entire drive train. Parts are very rare and there is no spare track anywhere I have found.
all from
http://www.steelsoldiers.com/tanks-apcs-etc/12146-m76-otter-pics-information.html
