502!! baby! just kidding, I would definately go with the the BB since you do want low end torque in a 4X4. I would not get the sb unless you know it has been built by a great engine builder, even if they have all the paper work showing what they bought to go into the sb, I still would not buy it until you found out who built it. They should have a dyno sheet to back up that kind of HP too. You could build the bb to have the same hp and it would last alot longer too.
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