Here’s what I found about the Mercedes‑Benz W210 series (which includes E210) equipped with a 3.45 rear axle gear ratio:

🛠️ What does ''3.45'' mean?

The ''3.45'' refers to a 3.45:1 final drive ratio—that is, the driveshaft rotates 3.45 times for every single rotation of the rear wheels  .

📦 Part Numbers & Compatibility

• A commonly used rear differential for W210 models with this ratio is stamped 2103510805, also cross‑referenced as A2023508214  .
• These are typically found in E‑Class sedans (e.g., E280 4Matic, circa 1996–2002).

⚙️ Which W210 models?

• Fits models like the E280 (W210) with automatic or AWD transmissions ().
• Note: diesel and some V8 models came with different ratios (e.g., 2.87, 3.07). The 3.45 is more common in V6 or manual-transmission variants  .

🔩 Physical Specs & Notes

• Housing design is the W210 standard; flange and cover vary slightly depending on whether differential is open, LSD, or has slip-skid (ASR).
• Swapping in a 3.45 differential typically requires matching the flange and ensuring compatible ABS/ASR fitment.

🔄 Why choose 3.45?

• Offers a sportier, quicker acceleration feel compared to higher numeric (taller) ratios like 2.87 or 3.07.
• However, fuel economy/cooling RPM at highway speeds will be slightly higher.

✅ Summary Table