← Mazda Miata NB (1999-2005 US model years)
Will 2004-05 Mazdaspeed Miata Torsen differential with MSM axles fit a Mazda Miata NB (1999-2005 US model years)?
Short answer: Yes, with extra parts or work. Confirmed
Yes, with extra parts or work: Two dealer guides agree the Mazdaspeed rear uses a larger Torsen unit and larger-diameter axles; it fits any 1999-2005 NB when the MSM axles come with it, and the MSM axles only work with the MSM differential.
| Part | 2004-05 Mazdaspeed Miata Torsen differential with MSM axles |
|---|---|
| Vehicle | Mazda Miata NB (1999-2005 US model years) |
| Years | 1999-2005 |
| Trim / condition | only as a set: MSM differential + MSM axles |
| Verdict | Fits with extra parts or work |
| Confidence | 3 of 3 — Backed by a manufacturer document, or two or more independent sources agree on a specific checkable fact. |
| Last verified | 2026-10-20 (date the cited sources were last read) |
Details
Two dealer guides agree the Mazdaspeed rear uses a larger Torsen unit and larger-diameter axles; it fits any 1999-2005 NB when the MSM axles come with it, and the MSM axles only work with the MSM differential. A forum poster also notes the MSM's inner axle shafts are larger. Final drive is 4.10.
Specs
- final drive: 4.10
Related build entries
Other drivetrain fitment for the NB
- NB 6-speed manual transmission (with NB shifter) — Reported to fit
- 1994-2005 differential, driveshaft and axles (7-inch rear) — Reported to fit
Sources
- NB Miata Compatibility Guide (NB2 to NB1) — Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) (vendor article; read 2026-10-20; full page read)
- Miata Torsen Differential Buyer's Guide — Redline Auto Parts (used-parts dealer) (vendor article; read 2026-10-20; search excerpt only)
- [NB] Stock NB 6 speed vs MS 6 speed — MX-5 Miata Forum (forum thread; read 2026-10-20; search excerpt only)
Summaries are in our own words. Fitment is not guaranteed — disclaimer.
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