First off, great how-to red. Everyone appreciates a good how to like this. The more how-to's the better.
However, to anyone considering doing this: If this is something that popped up out of the blue, the 3rd gear extender is only a band-aid for a bigger problem. Your shift fork, gear or syncro is worn and needs to be fixed. If you've always had this issue, the extender is indeed a possible solution and an excellent one at that. I believe even Pwerks will tell you this.
To the above poster: Billet Steel is very hard. Your shift forks are BRASS, a very soft metal. Your very hard gear selector pushes your very soft shift forks over your gears. If it isn't going in, the BILLET selector WILL DAMAGE YOUR SHIFT FORK. I don't know about you, but i'd rather replace a shift selector than a shift fork. You don't break shift sectors because your forks are too hard. You break them because you are shifting to hard or forcing your syncro into gear. It breaks for a reason. If it does not break, think about the added wear you are putting on your syncro and forks trying to force it into gear. You're just transferring the problem to another, more expensive area in your transmission.
You are very welcome, and appreciation is appreciated.
I agree that it is only a band aid, but until I get the funds for new gearset items, its a pretty effective bandaid. My Transmission has seen a lot of abuse. I do see a problem though with the fork vs selector paradigm. If you use the same strength metals, if they see enough force, they will chip, however using a softer metal for one alleviates this. This is probably most commonly seen in sledge hammers and wedges for splitting wood. You can see the wedge deforms and mushrooms, but the hammer is undamaged. It's not a bad idea, however somethings gotta give. It is much easier to replace a shift selector than a shift fork, but if the selector breaks, where do the fragments go? Answer: down into the gearset between the input and intermediate shafts. You might wind up pulling the gearset just to fish out the shrapnel. In either case, I would probably pull the gearset to inspect it, in case a fragment of the selector damaged something. It's not fun at all, but at least we don't have to drop the trans for either procedure.
On a side note you said something interesting: "You're just transferring the problem to another, more expensive area in your transmission."
My dad and I had a lengthy debate over this when I broke my IS. I figured the collar that breaks off is a "weak point" and a billet shaft would be the fix. He felt that the collar where it broke is a "weak point" that allows one part to fail, in effort to save many other parts. Sort of the "sacrificial shaft." While the shaft becomes a martyr, the gearset survives, instead of being shredded off the shafts, and in the case of 2004 and 05 models, damaging the needle bearings. IDK if its true in the case f the IS collar, but I do feel that once you strengthen one part, you put additional stress on another. And vice-versa, once a part is weakened or fails, it puts stress on other parts too.
I rebuilt my input shaft in January, but due to all the stuff you need to replace, I didn't have the cash for a new synchro, so I opted out, and got the 3rd gear extender instead, a few months later. Does it work? Yes. How long do I have before my synchro fails? IDK.