Matching the correct replacement bearing to a car alternator requires knowing which bearing the original equipment manufacturer (OEM) specified. This cross-reference guide covers the five major alternator brands — Bosch, Hitachi, Denso, Mitsubishi, and Valeo — and maps their alternator models to standard ISO bearing designations that any certified manufacturer can supply.
How Alternator Bearing Cross-Reference Works
Every car alternator contains two deep groove ball bearings:
- Front (drive end / DE): the larger bearing, nearest the pulley, handling higher radial loads from belt tension
- Rear (slip-ring end / SRE): the smaller bearing, supporting the slip rings, handling lower loads but at the same high RPM
Both bearings use ISO standard dimensions and can be identified by the model stamped on the outer race. The ISO designation gives you bore diameter (d), outer diameter (D), and width (B) — e.g., 6303 = d17 × D47 × B14mm.
OEM-specific prefixes (EC, NP, B-series) indicate additional fitment features for specific alternator housings. When sourcing replacements, you need the correct base dimensions plus the correct housing fit variant.
Bosch Alternator Bearing Cross-Reference
Bosch is the largest alternator manufacturer in Europe and supplies OEM to Volkswagen Group, Mercedes-Benz, BMW, and PSA. Bosch alternators appear under the NC (new construction), NI (new industrial), and F000AL series designations.
| Bosch Series | Front (DE) Bearing | Rear (SRE) Bearing | Notes |
|---|---|---|---|
| NC-series (most common) | 6303-2RS (17×47×14) | 6201-2RS (12×32×10) | Covers 70% of Bosch alternators |
| NI heavy-duty | 6304-2RS (20×52×15) | 6201-2RS (12×32×10) | Truck and commercial vehicle |
| F000AL (compact) | 6202-2RS (15×35×11) | 6001-2RS (12×28×8) | Small-displacement engines |
OTT equivalent: 6303-2RS, 6304-2RS, 6202-2RS, 6201-2RS, 6001-2RS — all in stock with Z3V3 noise grade.
Denso / Nippondenso Alternator Bearing Cross-Reference
Denso is the primary alternator supplier to Toyota, Honda, and many Mazda platforms. Denso alternators use an EC (expansion collar) front bearing in many models — this is a standard ISO bearing with two nylon expansion rings added to the outer diameter.
| Denso Series | Front (DE) Bearing | Rear (SRE) Bearing | Notes |
|---|---|---|---|
| 104210 series (Toyota) | ECB12-85D (15×35×11) | 6001-2RS (12×28×8) | EC = expansion rings on OD |
| SC series (Honda) | 6202-2RS (15×35×11) | 6001-2RS (12×28×8) | Standard smooth OD |
| High-output Denso | 6203-2RS (17×40×12) | 6201-2RS (12×32×10) | Larger bore for higher output |
OTT equivalent: ECB12-85D, 6202-2RS, 6203-2RS, 6001-2RS — see the full catalog for EC-series availability.
Hitachi Alternator Bearing Cross-Reference
Hitachi supplies alternators to Nissan, Subaru, Isuzu, and Mitsubishi vehicles. Hitachi models (LR, LRB designation) typically use slightly larger front bearings than Denso equivalents.
| Hitachi Series | Front (DE) Bearing | Rear (SRE) Bearing | Notes |
|---|---|---|---|
| LR series (standard) | 6203-2RS (17×40×12) | 6201-2RS (12×32×10) | Most common Hitachi bearing |
| LRB compact | 6202-2RS (15×35×11) | 6001-2RS (12×28×8) | Smaller output rating |
| Isuzu truck | 6304-2RS (20×52×15) | 6201-2RS (12×32×10) | Heavy-duty application |
Mitsubishi Alternator Bearing Cross-Reference
Mitsubishi Electric (not Mitsubishi Motors) manufactures alternators supplied to Mitsubishi vehicles, Chrysler, and various Asian OEM platforms. Mitsubishi uses NP (groove + snap ring) front bearings in many models.
| Mitsubishi Series | Front (DE) Bearing | Rear (SRE) Bearing | Notes |
|---|---|---|---|
| A2T series | NPB15-83D (17×47×14) | 6201-2RS (12×32×10) | NP = eccentric groove on OD |
| A3T / A5T | 6303-2RS (17×47×14) | 6201-2RS (12×32×10) | Standard smooth OD versions |
| A7T (high-output) | 6304-2RS (20×52×15) | 6201-2RS (12×32×10) | Truck / commercial vehicle |
Valeo Alternator Bearing Cross-Reference
Valeo supplies alternators to PSA (Peugeot/Citroën), Renault, and Fiat Group. Valeo A13/A14 series is one of the most common European alternators in the independent aftermarket.
| Valeo Series | Front (DE) Bearing | Rear (SRE) Bearing | Notes |
|---|---|---|---|
| A13, A14 (most common) | 6303-2RS (17×47×14) | 6201-2RS (12×32×10) | Same as Bosch NC |
| SG series (compact) | 6202-2RS (15×35×11) | 6001-2RS (12×28×8) | Small output variants |
| TG series (high-output) | 6304-2RS (20×52×15) | 6201-2RS (12×32×10) | Commercial vehicle |
Quick Reference: Most Stocked Alternator Bearing Models
For distributors building inventory, these six models cover the majority of alternator replacement demand across all major brands:
| Priority | Model | Dimensions | Covers |
|---|---|---|---|
| ★★★ | 6303-2RS | 17×47×14 mm | Bosch, Valeo, Mitsubishi front |
| ★★★ | 6201-2RS | 12×32×10 mm | All brands rear bearing |
| ★★ | 6203-2RS | 17×40×12 mm | Hitachi front, Mitsubishi |
| ★★ | 6202-2RS | 15×35×11 mm | Denso, compact Bosch |
| ★ | 6304-2RS | 20×52×15 mm | Heavy-duty / truck |
| ★ | 6001-2RS | 12×28×8 mm | Denso / Honda rear bearing |
For wholesale pricing on these models and OEM-specific variants (B-series, EC-series, NP-series), see the OTT alternator bearing catalog or contact OTT directly.
Related Resources
- Alternator Bearing Replacement Guide — sizes, symptoms, and how to choose
- Wholesale Alternator Bearings: Manufacturer vs Distributor — supply chain guide
- Denso Alternator Bearing Cross-Reference — detailed Denso-specific reference
- OTT Alternator & Starter Bearing Catalog — full wholesale catalog
![Alternator Bearing Replacement: Sizes 6201–6304, Symptoms & Guide [2026]](/images/products/ott-62303-2rs.jpg)
