Hey guys how can you tell a Bme 44 from a Bme 50 ? The pics I've seen they look the same. Help

Good question, it's not something you can determine from the muffler size as they are the same. This is taking me back many years and maybe something will come to me.
Have you tried here ?

http://www.bmeengine.com/engines.htm

Yes checked there sight,not a lot of info there