Looking at a Drive OM 139772. What year or boat did it come from? Is it possible to have had only 100 hours on it?

Anything is possible as far as a time used goes.

This serial number was on an 2002 boat out of SALEM OH, 44460

Drive serial number 0M139772 Model Number 5237200N1 MERCRUISER BRV 1X 1.50:1 made 09/24/2001 behind a 496 MAG HIGH OUTPUT ENGINE.