The pre-1947 trucks are extremely tight in engine compartment clearance. I'd strongly suggest pulling the front sheet metal before trying to remove the engine. You're likely to do quite a bit of damage to the paint and sheet metal trying to pull the engine/trans assembly otherwise. The crash box trans is a lot smaller and lighter than the SM 420, so it could probably stay attached.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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