I dont have all the pics I want right now for this, but I am going to give everybody an overview.

The problem exists on most all of the new t-cases. Be it a Jimmy, Tahoe, or a one ton dually. As already mentioned, the problem stems from the design.

The operation of the pump is in a nutshell like this. The pump is a floating design, it is aligned primarily with the mainshaft via a brass bushing and is allowed to float in the case using the tabs on the pump into slots in the case. The little clip is designed to take up the movement and dampen it. Problem is that that little spring steel clip takes a beating. Everytime you change load on the engine, that pump moves. On and off the gas is what does it, its not related to foward/reverse like plowing at all. Using 4x4 all the time or not at all means nothing either. The narrow edge on the pump will 'cut' through that clip over time and when the clip is damaged, that allows even more movement and it will start cutting into the case. The magnesium case is softer then the aluminum pump and thats why the case wears. Once the hole starts, its usually high in the case, above the fluid line so it dont leak at a stop or sitting. Only when moving is the pump pumping and this fluid is splashing up. You may never know about the problem until its too late. Usually by the time the problem is found, its too late and expensive repairs are ahead. There is no way of knowing what is damaged inside until its torn down, but most common would be the blocking rings and syncro parts, as well as the mainshaft sleeve. Lots more details on this, but I hope you get the overall view of it.

Now, for the fix. Seeing this problem a bunch of times, I had to figure out how to make it not a problem.

Here is what I came up with, sorry I dont have any side by side pics here. my computer crashed and i lost all of them, but I'll get more up.



What it is is a completely remade pump half, you can see that the tabs are now alot bigger (taller) and thus spread the load out better and prohibit the problem. The OEM pump uses the same tabs, but they are only about .090" tall, mine are .550" tall. This is only one half of the pump, not a complete replacment piece

I'll be getting with More Power in the near future on this and perhaps will be able to show you more detailed info on this as well as an overview on how its installed.