Sam,
Since the collets change by manufacturer, I am working on getting you the measurement from the end of the threaded end of the PTO crankshaft to the shield surface on the front bearing. This should get you an overall engine measurement you can use. I only have new unopened engines or used front exhaust/outboards in my shop that I can get you this measurement from, so to make sure you are getting an accurate overall engine length that you need, I am sure someone on here will have one open box 46 DD that they can measure and verify for you. Thanks.