For the DIY differential rebuilders this is a valuable tool needed to remove bearings and install them. It is actually the main universal part of a kit of many pieces that let you do all kinds of push and pull opperations. There are many special pieces that can be inserted into this main tool to fit different bearings the differential uses. The specific parts can be found in the diferential section of the service manual. OBTW, they don't come up for sale very often.
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