DETROIT – It’s What’s Inside that Counts. In the United States, the NV3500 manual transmission came from the factory in many Jeep models. The trouble is, many get confused by this, because there is also an NV3500 transmission available for Dodge. The NV3500 was developed by New Venture Gear, and on the Jeep, it compliments the 4.0L inline 6 engine.

This transmission looks nearly identical to the one used by GM and Dodge for light-duty trucks to the untrained eye. If one were to look closer however, they would see that the Jeep version bellhousing bolts to the transmission case. The most common GM medium duty transmissions mistaken for the NV3500 are:

  • The 1991 NVG 5LM60
  • The 1987 MG-290 MG
  • The 1988 HM-290 HM
  • The 1989 5LM60

Dodge Ram 1500

In 1993, New Venture Gear released the NV3500, while many of these older models have the same exterior appearance, there were massive overhauls and changes to interior parts with the NV3500 model. For example, the HM290 and the 5LM60 have four convoluted shift rails, while the NV3500 only has a single shift rail. The 5LM60 had issues with the input shaft and bearings that caused it to be failure prone until a second design was implemented.

The NV3500 expanded on this design, further improving upon it. Part of the reason the NV3500 manual transmission is such a tricky model is that all 5 of the models mentioned above can be substituted for each other as a complete unit, minus only a few minute details.

Jeep

A “drop-in” change out between a GM S and C/K trucks requires a modification to the length of the driveshaft, as well as altering the crossmember placement. This is because the C/Ks have a shorter tail shaft length than GM’s own S models. Another key difference is the master and slave cylinders. Both changed their bore measurements to metric from standard after the 1990s.

The master went from 11/16 to 18mm, while the slave went from 13/16 to 20mm. It is also important to note that transmissions of both Dodge and GM are not interchangeable. This is because the bellhousing and case of the transmission are both one piece, and they have different bolt patterns that are specific to each engine. Dodge utilizes unique specs for their input shafts, pilot diameter, and even spline count. These distinct features differ from GM, making the two incompatible. 

The Specifications

The Jeep NV3500 transmission was released by New Venture Gear in the year 2000 for the Jeep TJ Wrangler and the XJ Cherokee. This manual transmission was meant to be an upgrade from the AX15 model. This transmission was also present in several light-duty Dodge pick-up trucks. 2004 was the last year that the NV3500 was put in Jeep vehicles, after this point it was replaced by the NSG370 model, a 6 speed manual. The NV3500 is a five speed manual transmission that features top shifting, and is longitudinally loaded. The 4th gear is directly driven, while the 5th one is overdriven. All gears except reverse are synchronized and helically cut in the NV3500. 

The specifications for the transmission are as follows:

  • Make: New Venture Gear
  • Length: 16.7″
  • Weight: 97 lbs
  • Case: Cast Aluminum
  • PTO Port: None
  • Torque Rating: 300 ft. lbs.
  • Gear Ratio (Jeep): (x-to-1): 4.012.331.391.00.78R3.57

The spline count for the input shaft is 10 splines per 1 and 1/8″ diameter, there are some exceptions to that rule however. Some of the later NV3500 models that came out in 2004 Jeeps feature a surprising and impressive 19 splines per 1″ input shafts. The outer shaft has 23 splines, and is flush with the adapter flange’s rear transfer case. 

Compatibility

While transmission similarities can be a source of confusion, it also has the added benefit of making different models more compatible. The Jeep NV3500 was made to have the same transfer cases as the NP231 and the NP241OR. Because the NV3500 and the NP231 both have a 23 spline outer shaft, they are interchangeable. The NV3500 is also compatible with a number of different engines, including:

  • Buick V6
  • Chevrolet Small Block V6 and V8 
  • With some modification, the NV3500 can be adapted to the Jeep Amc 4.0 L I6 engine as well. 
  • Windsor Ford V8
  • Ford I6

It is important to note that some of these require adaptations, which can be done with conversion kits, or through manual modification if the mechanic is knowledgeable enough. 

In Closing

Before and leading up to when the NV3500 hit the market, there was a lot of progress and innovation being made in the transmission space. There were many small changes made in rapid succession that led up to big differences in outcomes. As a result, you have a period of time when it seems many transmissions are the same, but this is only external appearance.

Many subtle changes exist inside these transfer cases, much to the chagrin of mechanics and diyers everywhere. With just a little due diligence however, we can turn what seems to be disadvantage, to advantage. The interchangeability of the NV 3500 transmission should not be overlooked. Being able to use the same transmission (with only a few slight modifications) across several different makes, models, and engines, is an advantage that few transmissions can claim, even in modern manufacturing. 

What may seem at first glance like an unnecessary frustration, can actually help us when proper knowledge is applied. Another advantage of the NV3500 is that it is easier to find scrap parts for other manual transmissions thanks to its close relation to so many other models. A resourceful mechanic could create compatible, working transmissions across multiple models for much cheaper than others. While attention to detail is not something many want to deal with in today’s age of instant gratification, it is often these small details that are the difference between failure and success, boom and bust. 

This guest column was written by Luke Wilhoit, Managing Editor, CarPartPlanet.com