Hey guys my brother has a 1999 Subaru Impreza gc8 wrx I'm wanting to take his gearbox and wanting to know if it'll fit into my 2003 subaru Forester 2.5x na 

not sure if it will work or not, but you do need to be concerned about final drive ratios.. they MUST match between tranny and rear end.

Edited October 20, 20214 yr by heartless
cant spell today.. =P

http://www.gearhack.com/myink/ViewPage.php?file=docs/Subaru Transmission Chart

Anything is possible. Rear diff is almost certainly a different ratio, so that'll have to be swapped as well. Not ideal ratios for non-turbo and tall tires.

ASSuming the Forester is already a 5-speed. It will likely be a pull-style clutch, where the WRX will be push-style.  They should both be hydraulic, so you'll just use the WRX flywheel/clutch/slave cylinder.

I *think* a 99 aussie car will be phase 2, 8 bolt bellhousing. It's possible it's a phase 1, with 4-bolt bellhousing, in which case you'll be missing the lower starter bolt. There are about 6 ways to deal with this, documented thousands of times on the internet.

WRX is pull clutch, and the Forester is push clutch. But yes it can work. 

Must have matching rear diff or the same final drive. Most WRX's are 3.9 and the Forester is almost certainly 4.11

GD

It’ll bolt in no worries and will be physically the same in fitment. You’ll lose your dual range feature as the WRX box won’t have this.

You might find a difference in the front diff setup - impreza might still have the diff stubs, your 2003 forester will surely have the male stub axles. I don’t know if the impreza driveshafts will swap into the later model forester. 

You might find the gear ratios sluggish to work with the large tyres and the difference in revs between each gear will be different too. 

If the impreza box is a four bolt (stud on the lower starter motor mount is the easiest way to identify), it’ll be in the weaker phase 1 front case, but it could be a phase 2 eight bolt gearbox which is what your SG would have anyway. 

Cheers 

Bennie