Deutz BF4L913 4-Cylinder, Air-cooled Diesel Engine 

That one, sounds sooo good! You find so many good ones. I'll have to come up from Iowa, and visit sometime. : - ) Happy new year, and on to 2020!

what would be a good Deutz motor for an Exmark lazer Z zero turn mower

Do you rebuild duetz ftl511 s ? Where are you located ?