Convert Assebly to a Part

Yes This should be simple enough but not quite. I have an assembly of a Caterpillar Diesel Engine which is way to huge for use in my general arrangement. I downloaded it as a .stp at 161 meg but saved as assembly down to 51meg. Still too big and would like it as a single part. When I save it as part I lock up. Using SW 2009 Sp. 4.1. I tried save as part to components as well as faces and same result. Lock up.

Other save options work pretty quick like save as parasolid worked likety split but still brought it back up to 161meg. Just tried it as a test. Anyone have a suggestion on how to get this smaller as a part or something more manageable?

SolidworksAssemblies