In last month’s article we identified and explored the basics of the Magna Powertrain transfer cases found in late-model GM trucks. In this article we take an in-depth look at one of the three series of models available: the MP 1222, 1225 and 1226 models, using RPO (regular production option) code NQG.
Understanding the significance of the RPO codes on GM vehicles will make parts ordering simpler. Figure 1 shows the variations and descriptions of the NQG series of transfer cases. As these units are used in K1, K2 and K3 models of trucks, there are differences in input and output splines, chain size and number of pinions on the planets. These variations provide the torque capacity necessary to cover the different engine/transmission combinations for light-duty, heavy-duty and super-heavy-duty applications.
New Venture Gear, a manufacturing arm of Chrysler Corp., was bought some years ago by Magna International, one of the world’s premier supplier of parts to automakers around the world. The division that produces the transfer cases has been renamed Magna Powertrain. GM introduced a new series of transfer cases in mid-2007, and these units are now coming into our shops for work. This will be the first in a series of articles regarding these transfer cases and going over identification, theory of operation, and overcoming some design defects and issues that are now showing up in the marketplace.