That will be out of a car originally. It may have gotten under a truck at some point but only car rears had the pinion snubber.
Look for the BOM build of material number on the passenger side tube.
It should be a few inches out from the center section. Will be similar in forum of 602957-1 and should have some dates.
That BOM number will tell you what you need to know about the rear and how it was built from the factory.
Matt