Rob that engine stand has two 5" diameter ball bearings that the engine rotates on. I took the pictures after rotating the block so's I could stand up an' shoot them.
All is fine with that stand unless a customer's 11 year old son comes in and hits the rotation release with a Power Smoke diesel on the stand. If I had not seen him go for the release we'da had a 7.5 on the Richter Scale right there in the engine room. He actually released it and I caught it before it rolled over.