In general terms the clutch and pressure plate are centered with a guide and bolted to the flywheel, than the throw out bearing with the longer depth closest to the pressure plate springs slips onto the trans input shaft then engage the trans. The clutch fork usually just slips onto the throw out bearing without clips.
But we need to know what truck/engine you are referring to be specific.

Last edited by DrewP; 05/28/2013 7:57 AM.

Drew