What is a newer harley engine made of these days? Also when people go down or scuff up pieces, parts on the motor does it mess up any of the Integrity of tranny and motor connections or are they built for scrapes and bumps from time time? Are the only 2 connection points to the motor and tranny thru the front by the oil filter and thru the back part of tranny and swing arm?

Thanks, trying to understand how all of it goes together...kinda interesting