New Ratech pinion yoke holder tool.  This tool us a universal tool that fits many rear pinion yokes.  This is commonly used to hold the pinion will tightening the pinion yet when setting pinion bearing preload properly.  This will fit GM 9, 10, and 12-bolt differentials.  Typically, it will only use 2 of the 4 bolt holes.  You can use a 1/2" or 3/4" breaker bar on the plate.  This also has a puller that slides under the holder to push against the pinion to pull the yoke off. We use this same tool building rears at our shop.