Guys... Rebuilding a GM 10 bolt 8.2 rear end. Please explain the difference in a crush sleeve and a spacer. I ordered a rebuild kit from Summit which included a crush sleeve like the original which is about 4 inches long. Unfortunately it got crushed a little too far during setup. So, I thought it would be easy to go to the local GM dealer and get another. All they had was a little spacer about a half inch thick. Their mechanic said some pinions let you use the spacer instead of a crush sleeve. I opted to order the one like I had from Summit but I am trying to figure out what he was talking about....

They make a crush sleeve eliminator kit that uses a spacer and shims to set the bearing preload instead of the crush sleeve.

If you can't wait, some of these crush sleeves can be found at many parts stores in the HELP sections. O'Reilly is where I found mine , on a weekend. Seen the selections at Autozone and PartsAmerica.

They had ones like this http://store.summitracing.com/partdetail.asp?autofilter=1&part=RAT%2D3107&N=700+115&autoview=sku in parts stores which is what the dealer had. But mine had one like this http://store.summitracing.com/partdetail.asp?autofilter=1&part=RAT%2D3106&N=700+115&autoview=sku . I am just struggling to understand how they are interchangeable....

The short sleeve fits between a ledge on the pinion shaft and the front bearing as opposed to the longer sleeve fitting between the both front & rear bearing inner races.

Both serve the same purpose, but different routes of action.