The NSG370 transmission is one of the most capable six-speed manual gearboxes Chrysler ever bolted behind a Jeep engine — and if you're here, you probably already know that. Whether you're chasing down a whine, hunting for gear ratio data, or shopping for a NSG370 manual transmission to get your Wrangler back on the trail, this guide covers everything you need to know.
A Brief History of the NSG370 Manual Transmission
The NSG370 — short for New Venture Gear 370 — was developed through a joint venture between DaimlerChrysler and General Motors under the New Venture Gear brand. It entered production in the early 2000s and quickly became Chrysler's go-to six-speed manual for light-duty truck and SUV applications.
Jeep adopted the NSG370 starting with the 2005 model year, replacing the aging AX15 and NV3550 units that had served the TJ Wrangler platform for years. The NSG370 brought a taller overdrive ratio, improved shift feel, and better compatibility with the 3.8L V6 that powered the JK Wrangler from 2007 onward.
Vehicles that used the NSG370 include:
- Jeep Wrangler TJ (2005–2006) — paired with the 4.0L inline-six
- Jeep Wrangler JK (2007–2011) — paired with the 3.8L V6
- Jeep Wrangler JK (2012–2018) — paired with the 3.6L Pentastar V6
- Jeep Liberty (2005–2006) — NSG370 for the Jeep Liberty 2.4L
- Jeep Liberty (2005–2008) — NSG370 for the Jeep Liberty 3.7L
- Dodge Dakota (select years, limited application)
- Dodge Ram 1500 (select years, limited application)
The Jeep Wrangler application is by far the most common, and it's the primary fitment focus for most NSG370 replacement and rebuild work. If you're driving a TJ or JK, this is your transmission.
NSG370 Gear Ratios: What They Mean on the Trail and the Highway
Understanding the NSG370 gear ratios helps you make sense of how your Jeep behaves — whether you're crawling a rock ledge or cruising at 75 mph.
NSG370 Gear Ratio Specifications:
| Gear | Ratio |
|---|---|
| 1st | 4.46:1 |
| 2nd | 2.61:1 |
| 3rd | 1.72:1 |
| 4th | 1.25:1 |
| 5th | 1.00:1 |
| 6th | 0.84:1 |
| Reverse | 4.06:1 |
What this means in practice:
- First gear (4.46:1) is deep enough to give you meaningful mechanical advantage in technical terrain, especially when combined with a 4:1 transfer case low range.
- Fifth gear (1.00:1) is your direct drive — no multiplication, no overdrive. This is your highway cruise gear for moderate speeds.
- Sixth gear (0.84:1) is a true overdrive, dropping engine RPM at highway speeds and improving fuel economy. At 70 mph, the difference between 5th and 6th is noticeable on the tachometer and at the pump.
- Reverse (4.06:1) is nearly as deep as first, which is useful when you need to back out of a technical situation with control.
For most Wrangler owners running 35-inch tires and a 4.10 axle ratio, the NSG370's spread works well. If you've gone to 37s or larger, you may feel the gaps between gears more acutely — but that's a tire and axle conversation, not a transmission problem.
NSG370 Identification and Fitment Considerations
Before you order a replacement, you need to confirm you have an NSG370 and understand what fits your specific application.
How to identify an NSG370:
The NSG370 has a distinctive aluminum case with a cast identification tag on the driver's side. Look for the tag near the mid-case area — it will reference the gear unit number and build date. The transmission is a six-speed unit with a top-mounted shifter and a relatively compact footprint compared to older Jeep manual transmissions.
Fitment variables to know:
- Input shaft: The NSG370 uses a 23-spline input shaft in most Jeep applications. Confirm your clutch disc and flywheel are compatible before ordering.
- Output shaft / transfer case interface: The NSG370 mates to the NV241 (Rock-Trac) and NV241OR transfer cases in JK applications, and the NV241 in TJ applications.
- Bellhousing: The bellhousing is integrated into the transmission case. Fitment is engine-specific — the 4.0L TJ application and the 3.8L/3.6L JK applications are not interchangeable without additional modification.
- Model year matters: A 2005–2006 TJ NSG370 is not a direct bolt-in for a 2012–2018 JK. Always confirm year, engine, and transfer case before purchasing. TJ owners on the 4.0L should look at our TJ-specific NSG370 replacement for a confirmed-fit unit.
Not sure which unit covers your engine? Browse our NSG370 transmission for multiple engine applications to see if your configuration is covered.
When you order a Jeep Wrangler NSG370 6-speed from Tennessee Standard Transmissions, our team verifies fitment against your specific application — so you're not guessing at compatibility.
NSG370 Fluid: What to Use and When to Change It
Fluid selection is one of the most debated topics in the NSG370 community, and for good reason — using the wrong fluid causes premature wear and notchy shifting.
OEM fluid specification:
Chrysler specifies MOPAR Manual Transmission Lubricant (MTL) for the NSG370. This is a low-viscosity, friction-modified fluid — not a conventional gear oil. The NSG370 does not use standard 75W-90 or 80W-90 gear oil. Using a conventional gear lube in this transmission is a common mistake that leads to hard shifting, especially when cold.
Acceptable alternatives:
Many Jeep owners and transmission shops use Pennzoil Synchromesh or GM Synchromesh fluid as a compatible substitute. These are purpose-built synchronizer-compatible fluids that match the friction requirements of the NSG370's brass synchro rings.
Fluid capacity:
The NSG370 holds approximately 2.0–2.2 quarts of fluid. Always fill to the level of the fill plug, not by volume alone.
Service interval:
Most experienced Jeep technicians recommend changing NSG370 fluid every 30,000–45,000 miles under normal use, or sooner if the transmission has been submerged, run hot, or shows signs of contamination. If you've done water crossings, check the fluid color — milky or gray fluid means water intrusion and you need to act fast.
Common Reasons Jeep Owners Replace or Rebuild an NSG370
The NSG370 is a durable unit, but it's not indestructible. Here are the most common failure modes that bring Jeep owners to the point of replacement:
1. Worn or damaged synchronizers
The most frequent complaint is difficulty engaging 2nd or 3rd gear, especially when cold. This is almost always a synchronizer issue — either worn brass synchro rings or damaged blocker rings. Using the wrong fluid accelerates this failure significantly.
2. Bearing noise
A whine or growl that changes with vehicle speed (not engine speed) typically points to worn input or output shaft bearings. Left unaddressed, bearing failure leads to case damage and a much more expensive repair.
3. Gear engagement issues / jumping out of gear
If the transmission pops out of a specific gear under load, the shift forks, detent springs, or gear engagement dogs are likely worn. This is a safety issue and should not be ignored.
4. Leaks
The NSG370 can develop leaks at the input shaft seal, output shaft seal, or shift tower gasket. A transmission that's been run low on fluid may have internal damage that isn't immediately obvious.
5. Physical damage from off-road use
Rock strikes, hard landings, and trail abuse can crack cases, bend shift forks, or damage the tailhousing. If the case is compromised, a replacement unit is often more cost-effective than a repair.
6. High mileage wear
At 150,000+ miles, many NSG370 units simply reach the end of their service life. If you're experiencing multiple symptoms simultaneously, a remanufactured replacement is often the most economical path forward.
Why Buy a Remanufactured NSG370 from Tennessee Standard Transmissions
At Tennessee Standard Transmissions, we specialize in remanufactured manual transmissions — and the NSG370 is one of our core units. Here's what sets a TST reman apart from a used pull or a generic rebuild:
Full remanufacture, not just a rebuild
Every NSG370 that leaves our shop is completely disassembled, cleaned, inspected, and rebuilt to factory specifications using new bearings, seals, synchronizer rings, and wear components. We don't patch — we remanufacture.
Fitment-verified before it ships
We confirm your year, engine, and transfer case before your unit is built. You're not getting a generic "fits most" transmission — you're getting a unit built for your specific application.
Warranty you can count on
Our remanufactured transmissions are backed by a real warranty. We stand behind our work because we know what goes into it.
Core exchange program
Send us your old unit and we'll credit your core. It's a straightforward process that keeps costs down and gets you back on the road faster.
Browse our full lineup of manual transmissions or go straight to our replacement NSG370 transmission — built and ready to ship.
Conclusion
The NSG370 is a well-engineered six-speed that served the Jeep Wrangler platform for over a decade — from the last of the TJs through the end of the JK generation. When it's working right, it's a capable, confidence-inspiring gearbox. When it's not, the symptoms are hard to ignore.
Whether you're diagnosing a shifting problem, planning a proactive replacement, or just doing your research, understanding your NSG370 transmission puts you in a better position to make the right call. And when it's time to replace it, Tennessee Standard Transmissions builds the unit you need — correctly, completely, and backed by people who know Jeep manual transmissions inside and out.
Frequently Asked Questions: NSG370 Transmission
Q: What vehicles use the NSG370 transmission?
A: The NSG370 was used primarily in the Jeep Wrangler TJ (2005–2006) and Jeep Wrangler JK (2007–2018). It was also used in the Jeep Liberty (2005–2008) and limited Dodge Dakota and Dodge Ram 1500 applications.
Q: What fluid does the NSG370 take?
A: The NSG370 requires a low-viscosity, friction-modified manual transmission fluid — specifically MOPAR Manual Transmission Lubricant (MTL) or a compatible substitute like Pennzoil Synchromesh or GM Synchromesh fluid. Do not use standard 75W-90 or 80W-90 gear oil.
Q: What are the NSG370 gear ratios?
A: 1st — 4.46:1, 2nd — 2.61:1, 3rd — 1.72:1, 4th — 1.25:1, 5th — 1.00:1 (direct drive), 6th — 0.84:1 (overdrive), Reverse — 4.06:1.
Q: Is the NSG370 from a TJ Wrangler the same as the one in a JK Wrangler?
A: No. While both are NSG370 units, the TJ (4.0L) and JK (3.8L/3.6L) applications have different bellhousing configurations and are not direct bolt-in swaps for each other.
Q: Why does my NSG370 shift hard when cold?
A: Hard cold shifting is almost always related to fluid. If the transmission has conventional gear oil instead of the correct synchromesh-compatible fluid, the synchronizers won't engage properly until the fluid warms up.
Q: How long does an NSG370 last?
A: With correct fluid and normal use, an NSG370 can last 150,000–200,000 miles or more. Premature failure is most often caused by incorrect fluid, water intrusion, or deferred maintenance.
Q: What's the difference between a rebuilt and a remanufactured NSG370?
A: A rebuilt transmission replaces worn parts as needed. A remanufactured transmission, like those built by Tennessee Standard Transmissions, involves complete disassembly and replacement of all wear components to factory specifications regardless of visible condition.
Q: Can I rebuild my NSG370 myself?
A: Technically yes, but it requires specialized tools and a solid understanding of transmission assembly. For most Jeep owners, a professionally remanufactured unit is a more reliable and cost-effective solution.