Engine Mounts

[crsgmc]

I have been reading this board for quite a while but this is my first post. I am replacing the engine on my 1996 GMC K1500 with a new GM crate 350. I am about half way done and things are going well. My question is that the motor mounts have a secondary bracket on them in addition to the standard clam single motor mount. The passenger side is missing this second motor mount bracket. What purpose do these serve. I checked GM's web site and I did not recognize the part in the schematic. By checking the numbers on the old engine, it is not the original engine in the truck. I don't have much history on the truck. Maybe someone can shed some light on the subject, like the part name.