The spacers I see in the picture above the adapter plate for the engine have nothing to do with the engine stand adapter. They just happen to be on the same page. They go between the intake manifold and the head. They allow a larger ported manifold to be used on a smaller head. I have used them on to mount a 2 barrel carb on a 270 engine. Apparently these are for Chevrolet. They may or may not fit GMC but the idea is the same. I use a OTC 1735B and I don't need an adapter, but most engine stands are universal and have arms that adjust for different engines. If I had a universal stand that is not supported on both ends, I would definitely use the adapter plate. It scares me every time I see someone working on an engine that is bouncing around. Before I got my OTC stand, I used to bolt a 2x4 to the water pump holes and use that for a leg. Even with a stand with wide spread legs, it would scare me to torque head bolts or main caps with the engine unsupported in front and a universal adapter in the rear.
I think originally I was talking about the manifold spacers and the other question was the spacers for the engine stand.
