The Novak Guide to the

New Process 435 Transmission

np435_transmissionThe 435 is an excellent, heavy-duty truck transmission designed and used in ½, 3/4 and 1+ ton trucks. It is a well-built transmission and remains easy to locate and generally inexpensive to buy and maintain. The strength, relatively short size and the gearing of the transmission make it a good choice for a variety of situations.

The NP435 was made by New Process Gear from 1962 thru 1997. They are found primarily in Ford trucks from 1966 to 1992 and Dodge trucks from 1962 to 1993. They also had limited distribution in GM & Chevrolet trucks from 1968-1972. They are also found in some International Harvester and industrial applications.


This transmission is 10.8" long and features an aluminum top cover that is retained by eight bolts. The NP435 case is of cast iron.

The Ford NP435 has a 1-1/16" diameter, ten spline input shaft that has a stick-out of 6-1/2" from the front face of the transmission. The pilot tip of the transmission measures ~17mm. The front bearing retainer flange measures 4.85" and the bearing retainer tube is 1.43" in diameter. The front bolt pattern is the symmetrical Ford "butterfly" pattern; roughly 8-1/2" wide by 6-5/16" tall.

The early Dodge NP435 up through 1968 had a 10 spline, 1" OD input shaft. Dodge units after 1968 have a 23 spline input shaft with an 8-3/8" stickout. The Dodge NP435 featured two different styles of front input shaft & bearing retainer. The earlier and less common style (from 1962-) generally used a deep ball roller bearing input. These earlier units are not compatible with our conversion assemblies. While ball bearing front versions still persisted in some applications, they were rarer after 1969. The more common and later style featured a tapered roller bearing and cup assembly. These later versions are compatible with all of our adapter assemblies.

The GM / Chevrolet NP435 has a 10 spline input shaft with a 6-1/2" stick-out length. This version was only available with the roller style input bearing instead of the later and more common tapered bearing design. None of the GM NP435's are compatible with our adapter assemblies.

The shifting pattern for all of the 435's is in the standard "H" pattern with reverse gear being to the right side, and down.

1st 2nd 3rd 4th (direct) Rev.
NP435A (Dodge, GM) 4.56 2.28 1.31 1.00 5.64
NP435L (Ford, Dodge, GM) 6.68 3.34 1.66 1.0 8.26
NP435D (GM) 4.90 2.29 1.19 1.00 6.06
NP435E (Ford) 6.68 3.34 1.74 1.00 8.26

There may be no tagging nor proper tag interpretation to know which version of the 435 one may have. However, if trying to identify by the third gear ratio, one should count the mainshaft third gear teeth; 23 teeth for 1.66:1, 24 teeth for 1.74:1 and 25 teeth for 1.31:1.

Note that we have encountered a version of the NP435 with a helically steeper cut 2nd gear, which does not interchange with the overwhelming majority of 2nd gears, nor mesh with the corresponding cluster shaft gear. The tooth count and gear ratio are the same.


np435_specsThe NP435 is a top loaded, top shifting truck style transmission. The NP435 enjoys a very low compound gear at 6.68:1 and as such it is a popular choice for those wanting a very low crawling gear. Note that some Dodge versions of this transmission offered a taller first gear of 4.56-to-1.

The NP435 features a power-take-off (PTO) port on the passenger side of the case.

Transfer Case Adaptability

This transmission makes an excellent conversion transmission due to its adaptability into most Jeeps. Both 2wd and 4wd versions of the NP435 can be used equally well, and there are no inherent advantages to either one once you have installed our adapter assembly.

The Ford and Dodge 435 can be adapted to the popular Jeep (and many IH) transfer cases, including the:

2wd & divorced 4wd & Dana 21 adapter pattern

4wd (married) adapter pattern

There are two-wheel-drive and four-wheel-drive models; the critical difference being in the bolt pattern of the rear adapter housing or tail housing. Ford 4wd trucks with the remote (commonly termed "divorced") mounted transfer cases actually have the two-wheel-drive bolt pattern on the rear face and the installer should make this distinction when ordering the adapter assembly. Of note, the NP435's as married to the Dana 21 (single-speed transfer case) featured the 2wd pattern.

The Chevy / GM versions of the NP435 is different in its design, fairly rare and we do not support these adaptations. The installer can consider the SM465 as a very good alternative.

Engine Compatibility and Adaptability


The front face bolt pattern of the Ford NP435. This particular version has been cast without the extra, undrilled ears that are useful when adapting to a GM bellhousing.

Dodge & Ford

As the reader will conclude, the Dodge NP435 will marry directly to a Dodge style bellhousing. Likewise for the Ford NP435 and its bellhousing compatibilities.

AMC Jeep

The Ford NP435 is also an excellent candidate for AMC Jeep bellhousings made from 1976 to 1986 that were married to the T150, T18 and T176 transmissions, or otherwise have an available bellhousing bolt pattern of 8-1/2" wide by 6-5/16" tall. They are readily compatible with these engines and bellhousings, and need only a custom pilot bushing. For more details, see Adapting Ford Transmissions to AMC Bellhousings for details.


Many of the Ford NP435's have two extra undrilled ears cast into the front face of the transmission case. This is important if you intend to run it behind a GM bellhousing. The transmission having these extra undrilled ears will greatly simplify its use with GM engines. For more details, see Adapting Ford Transmissions to GM Bellhousings.

Rebuilding the NP435

A Cautionary Issue on Towing
Improperly flat-towing (pulling a vehicle not under its own power) any vehicle with the NP435 transmission can cause the very prompt destruction of third gear bore and its mainshaft journal due to insufficient oiling.

If you must flat-tow, and have a transfer case, you may set it in full neutral and place the NP435 in any gear to prevent mainshaft spin. However, note that many transfer cases themselves do not allow for flat towing.

Preferably, you may wish to disconnect the rear drive shaft. Rear axle lockout hubs may be a worthwhile addition for this reason.

We have seen and heard of a few incidents of this over the years, the worst of which producing a complete friction welding of third gear to its mainshaft.

This is one of the only quirks of the 435, and easily avoidable.

Rebuild and repair parts for the NP 435 transmissionThe NP435 is relatively simple to rebuild. Many shadetree mechanics do very outstanding rebuilds if they have access to a press, snap ring pliers and bearing pullers. Many choose to do a full rebuild during the adaptation process, and our instruction guides feature all the details, diagrams, pics and tricks required to do professional level work.

When filling your 435 with gear oil, we recommend that you select a conventional mineral oil or a para-synthetic in lieu of a full synthetic oil. Properly assembled manual gearboxes do not have the thermal strains seen by combustion engines or hypoid gears. Synthetic fluid in these gearboxes, while not harmful, is probably an economic waste.

Hypoid gear oil is sulphurized higher than transmission oil and can be mildly corrosive to the non-ferrous alloys used for synchros, bushings and thrust washers in these transmissions.

An 80W-90, API-GL5 or MT-1 rated fluid is very good. Some claim faster shifts from using a 50W engine oil in their transmission and we do not consider this to be contraindicated unless you operate your vehicle in a very warm environment.