Well I figured I would post the process that I followed to fit the Yokomo gear diff in the TC6. I know that there are lots of opinions on how to do this, but this is the process that I followed and think it works pretty well. I am not advocating that anyone else try this, and if you do you take full responsibility for the outcome. I would say that this project is medium difficulty and will take about an hour or two to complete.
If you do attempt to do this please wear a mask and eye protection, especially on step 2.
Step 1) Remove the diff out drives from the gear diff housing. Please follow the provided instructions on this. The reason I do this is that the diff out drives get hot when grinding on them so it it best to not have it in contact with the plastic diff housing. Make sure you do both drive cups.
Step 2) In order to fit the longer AE CVAs it is required that you deepen the out drive cup. I did this by grinding a deeper groove in the bottom of the drive cup using a reinforced cut off wheel on my dremel. You don't have to go very deep but you want to remove about .25 mm of material and also square off the bottom of the out drive grooves. The idea here is that we need to get the CVA ball end and blade deeper into the out drive.
Step 3) It is time to trim the diff housing so that it will fit into the bulked. The idea here is to trim the lip that stops the belt tensioner so that the belt tensioner assembly can move closer to the center of the diff. I removed about .35mm of material. It is important that this be as straight as possible so that it will fit in the bulked straight. I once again used a cut off wheel in my dremel to accomplish this.
Step 4) You can now assemble the diff with your required oil and test fit the diff in the bulked. Based on how much you took off you may or may not need the shims that are required for the stock diff. I am not currently using any in my cars. For mod I am running 1000cst and for stock I am running 700cst!
Step 5) It is now time to grind down the CVA ball end so that it can fit without bind in the drive cup. I ground down the sides of the ball and was careful to stay clear of the pins. It is important to grind off enough material from both sides of the ball, and after you do this it will not look like much of a ball anymore. It is important to test fit as you go and ensure that you take off only enough material to make them fit without bind. Be patient here and be careful.
Step 6) The last step to remove some material from the CVA blade. It is important to narrow the section that fits the furthest into the drive cup and also remove some material (and flatten) the bottom of the blade. The idea here is to remove enough material so that the blade fits in the drive cup without any bind.
Once you have completed all of this test fit everything and make sure that the CVAs do not bind in anyway during rotation and arm movement both up and down.
Like I said there are lots of ways to do this and if I had it my way I would have used an end mill to do all of the metal work. But lets get real not very many of us have access to stuff like that. I was able to make three gear diffs fit with just the use of some patience and my dremel. Not the prettiest looking thing, but it works!
Good luck and I hope this helps anyone considering doing this until the actual AE gear diff comes out, which I hope is soon!