How reliable is this fitment answer?

Confidence: Reported (2 of 3). Stated by one reasonably reputable source (retailer, shop, magazine). Not independently confirmed. Based on 3 cited source(s), last verified 2026-10-20.

← Subaru WRX (GD/GG, 2002-2007)

Will STI R180 rear differential fit a Subaru WRX (GD/GG, 2002-2007)?

Q: Will STI R180 rear differential fit a Subaru WRX (GD/GG, 2002-2007)?

Yes, with extra parts or work. Sources agree WRX rear axles do not fit the R180, so the swap brings STI rear axles, hubs and knuckles, rear brakes that suit them and a parking-brake solution. Driveshafts need a matching yoke (a NASIOC thread lists Subaru 38358AA000 to put a WRX auto shaft on an R180). Ratio must match the front: 3.90 for a 2004-05 STI box, 3.54 for 2006-07. Involves brakes and hubs, so capped at Reported.

Short answer: Yes, with extra parts or work. Reported

Yes, with extra parts or work: Sources agree WRX rear axles do not fit the R180, so the swap brings STI rear axles, hubs and knuckles, rear brakes that suit them and a parking-brake solution.

Years: 2002-2007 · Applies to: only with STI rear axles, hubs/knuckles and matching rear brakes · 3 sources · Last verified 2026-10-20

Safety-critical part. This claim comes from community or vendor sources, not the vehicle or part manufacturer, so its confidence is capped at "Reported". Have the work done or checked by a qualified professional and confirm part numbers with the manufacturer.

Part	STI R180 rear differential
Vehicle	Subaru WRX (GD/GG, 2002-2007)
Years	2002-2007
Trim / condition	only with STI rear axles, hubs/knuckles and matching rear brakes
Verdict	Fits with extra parts or work
Confidence	2 of 3 — Stated by one reasonably reputable source (retailer, shop, magazine). Not independently confirmed.
Last verified	2026-10-20 (date the cited sources were last read)

Details

Sources agree WRX rear axles do not fit the R180, so the swap brings STI rear axles, hubs and knuckles, rear brakes that suit them and a parking-brake solution. Driveshafts need a matching yoke (a NASIOC thread lists Subaru 38358AA000 to put a WRX auto shaft on an R180). Ratio must match the front: 3.90 for a 2004-05 STI box, 3.54 for 2006-07. Involves brakes and hubs, so capped at Reported.

Specs

ratio 2004 05 sti: 3.90
ratio 2006 07 sti: 3.54
type: clutch-type LSD (per NASIOC FAQ)

Related known issues

Stock transmission/clutch is the fuse under extra power

Related build entries

STI 6-speed swap

Other drivetrain fitment for the GD

2004-2007 US STI 6-speed manual transmission — Fits with extra parts or work

Sources

FAQ: STi 6MT Swap into a WRX — NASIOC forum (forum thread; read 2026-10-20; search excerpt only)
The end all 6 speed swap information thread — NASIOC forum (forum thread; read 2026-10-20; search excerpt only)
STI 6-Speed Swaps - Everything you need to know — Flatirons Tuning (swap-kit vendor) (vendor article; read 2026-10-20; full page read)

Summaries are in our own words. Fitment is not guaranteed — disclaimer.

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