New Process NP440 Manual Transmission

NP440, NP833 Transmission Specs & Ratios

The New Process NP440 manual transmission can be found in, amongst other applications, 1981 to 1987 GMC and Chevrolet pickups equipped with the 6.2L Detroit/GM diesel engine. For all intents and purposes, the transmission designations NP833 and NP440 can be used interchangeably, although records suggest that General Motors marketed the transmission (RPO code MY6 in GM pickup applications) as the NP440 in an effort to avoid confusion with Chrysler's New Process A-833, which was used extensively in Mopar applications beginning in 1963. Although the transmission platforms are similar in nature, this article focuses on the NP440 used by GM in 6.2L diesel applications.

The NP440 is a bit of an oddity in the fullsize pickup realm - it's a side-loading, four speed, overdrive transmission. First gear is relatively high (lacking a "granny" low), and fourth gear is a 0.73 to 1 overdrive ratio instead of the direct drive fourth gear typical of the period. The result was a gearbox that favored fuel efficiency but lacked the performance characteristics of transmissions such as the Muncie SM465, also available in 6.2 diesel applications. The NP440 is easily recognizable by its unique shift knob label, which reads "OD" in the traditional 4th gear position. Because of the transmission's 'uniqueness', it is somewhat rare.

While the Chrysler A-833 is well renowned for its strength, being used in applications including those powered by the legendary 426 Hemi and 440 Magnum big block V-8s, it's suggested that the NP440 features a maximum input torque capacity in the 270 lb-ft range. The NP440 features identical input and output splines to that of the Muncie SM465, characteristic of the fact that the transmissions were used in identical applications.

 

NP440/NP833 Transmission Ratios

1st

2nd

3rd

4th

R

3.09 : 1

1.67 : 1

1.00 : 1

0.73 : 1

3.00 : 1

 

NP440/NP833 Transmission Specs

Transmission:

New Process NP440 (NP833)

Type:

Side loading 4 speed overdrive manual transmission

Manufacturer:

New Process Gear

Model Years/Applications:

1981 - 1987 GMC, Chevrolet fullsize pickups (RPO code MY6)

Synchronized:

Synchronized in all forward gears

Case Material:

2WD cases were produced from cast iron or aluminum, 4WD cases were produced from cast iron only

Case Length:

10 5/8"

Input Shaft Splines:

10 spline

Output Shaft Splines:

27 spline

Max Input Torque:

~ 270 lb-ft

Weight:

~ 125 lbs (cast iron case)

Shift Pattern:

New Process NP440 shift pattern