The Desert Sled has some frame reinforcements compared to the other models (see green arrows below). There may be other reinforcements, these are just the ones I can visibly see.
I'm not faulting you for taking the Full Throttle off-road, I would have done the same. Based on what you experienced, do you think the Desert Sled frame reinforcements would have prevented the cracked left hand side engine case?
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Cafe Racer without the frame reinforcements:
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