Okay, everybody, sit round and listen up. Here's the skinny.
First off, before I get started, I want to say DO NOT PUT A 2008 IMPREZA SHIFTER IN YOUR CAR!
I learned the hard way, several times, that the new 08 GE/GH Impreza shifter is not the same as the GD/GG shifter. I installed it anyway (because I got such a good deal on it), but it required a LOT of fabwork, and had I gotten the same deal on a GD/GG shifter, I would have easily taken it.
As for the debate over what parts are needed and why... well, here are your answers.
The old-style Subaru shifter looks like this. Pay close attention to the upper linkage:
Here's the bracket off the old shifter, again, pay close attention to its shape:
Now, here is the 08 WRX shifter, and again, pay close attention to the upper linkage:
Now, here's the bracket for the new shifter, again, pay close attention to its shape:
Can you see the difference? The linkage is essentially reversed. THAT'S why you need the bracket off the new-style shifter.
NOW... you must get the bracket that goes by the part number 35047AC030 as others have said. But that's not the bracket pictured. The bracket pictured is 35046AG020 for the 08 WRX. This bracket does not have a little hole for the shifter return spring to grab onto. I guess maybe the 08 WRX transmission has an internal spring. So unless you want your shifter to flop around like a... well... you know, you MUST get the 35047AC030 bracket.
Now, continuing...
You also need the bolt that goes by the part number 35045FC000. The reason is that that bolt has its own sleeve on it which fits snugly in the bushings that come with the 35047AC030 bracket. You CANNOT use the sleeve and bolt from either your old shifter or the 08 WRX shifter, because they will not fit in the 35047AC030 bracket.
But wait... the 35045FC000 bolt doesn't just fit into the 08 WRX shifter either:
The sleeved portion of the bolt is too fat... so you have to drill the hole bigger - I used a 3/8 size drill bit and still had to scrape the drill bit around the edges of the new hole just to make it big enough:
See?
Ahh, that's better. This is what it looks like complete:
Now don't make the stupid mistake I did. I drilled the hole above the shifter, so the bolt would have to be inserted from the top of the shifter while in the car. Although that adds a tiny bit of safety to it (should the nut ever come off the bolt, the bolt won't fall out), that made putting the bolt in A LOT harder, because the body of the car is just close enough to the shifter assembly that it won't allow the bolt to go straight in. You'd need to have the entire shifter assembly dangling out the bottom of the car for you to be able to get the bolt in... or at least that's what I had to do.
Now, moving on...
That's not even close to being the only problem.
The biggest problem with the whole installation was that the 08 WRX shifter is TOO LONG:
Compare the pocket where the ball of the shifter sits. See how it's about an inch longer than the old one?
That meant that, without fabwork, it would NOT fit in the car at all. With the back of the shifter sticking out the rear mount and hitting against the body of the car, the front circular mount would NOT fit over the bolt on the transmission.
So I had to grind the back of the shifter off:
But that wasn't the end of it either.
I figured, since I was going through all this hassle, I'd at least improve the shift feel a bit by getting some Kartboy shifter mounts.
But the rear Kartboy mount is significantly longer than the stock mount, which meant that even with the end of the new shifter ground off, it still was too snug of a fit.
So I completely ruined whatever warranty or return policy that came with the Kartboy mounts and ground off part of the rear Kartboy mount:
Just FYI, grinding any rubber or polyurethane with a grinder will essentially melt it due to the heat, and it is NOT fun spilling melting hot polyurethane on your bare hand.
Anyway, so that was enough for me to mount the shifter assembly in the car.
But it wasn't going to give up quite that easily.
The front mount of the 08 WRX shifter, while it does not appear to be any narrower, apparently is, because when I had it mounted on initially, it would slide back and forth about a millimeter between the transmission and the big washer that holds the shifter return spring. So I bought some washers (a quarter is in the picture for size comparison):
... and they were big enough to take up the slack, so that when I tightened the nut down, it squeezes the front mount securely.
So now the 08 WRX shifter is successfully installed in my car.
You can see in this picture where the pocket in the shifter is right up against the rear mount, thus necessitating me to grind it down:
And although it's not easy, you can see the washers on either side of the front mounts:
So... how does it feel?
Well, one of the first things I noticed about the 2008 WRX when I sat in it is how the shift pattern has moved. I'm not sure why, but Subaru moved the shifter down (towards the rear of the car) and to the right (towards the passenger seat). That probably explains why the shifter is longer. Seriously, drive your 5spd Legacy to a Subaru dealer, immediately get out of it and get into a 2008 WRX and play with the shifter. The whole shift pattern feels about an inch farther away from you toward the passenger and also down a bit toward the rear of the car.
And now that's how my car feels.
It might make more sense if I say that where my first gear is now is about halfway forward into where it used to go into 3rd.
This is where my 1st gear is now, notice how far forward the shift boot is:
And this is where my neutral is. Notice how the boot is actually bent backwards slightly:
I don't know if it's necessarily a bad thing, but it will take some getting used to, that's for sure.
Truth be told, I haven't even gotten to mounting the plate back onto the rubber sealing boot underneath the trim inside the car, because now that the shifter has moved, I'll likely have to drill six new holes to make that plate fit. I'll do that later. I just wanted this car out of my own garage and back on the other side where it belongs, so my Honda can sit in my garage and I don't have to go to the other side of the house to get to work in the morning.
So anyway, aside from the strange 'moved' shift pattern, it does feel nice and firm, and even though I used a stock 08 WRX shifter (not an STi short-throw), the throws are still significantly shorter than my original shifter. So the overall impression is still good.
But for God's sake, use a GD/GG shifter, unless you really like to torment yourself for no good reason, then fab the GE/GH shifter to work.
Oh, and bonus sneak peek partial nighttime picture of what wheels I have on my car right now:
Just so it's easier, the only part numbers you ABSOLUTELY MUST NEED TO KNOW to make a new-style shifter fit are these:
1) 35047AC030
2) 35045FC000
You can use a stock shifter like I did, or an STi short-throw, but you will still need those two part numbers to make it fit.
