Note: This page is intended as aftertreatment education. Skyline does not sell any of the part numbers that brought you to this webpage. However, as explained below, there are assemblies that contain parts sold by Skyline, so if you think your assembly contains a DOC or DPF, contact Skyline for assistance.

Aftertreatment devices (ATD) are assemblies of multiple aftertreatment components, like the combination of an inlet module, a DOC, a DPF, an outlet module, plus sensors, clamps, gaskets, and other components. Some manufacturers mark the ATD part number (or ASM part number, ASM for "assembly") on one of the components in the aftertreatment system, and so people search for those numbers on the Skyline website.

There appear to be several kinds of ATDs:

• ATDs containing a DOC, a DPF, and clamps, gaskets, and etc. These are most common on pre-2017 aftertreatment.
• ATDs containing SCR components. These are most common on pre-2017 aftertreatment, such as on the two module systems.
• ATDs with DOC, DPF, and SCR, like the US17 single-module systems used by Cummins, Navistar, Paccar.
• 1-Box systems from Detroit Diesel and Volvo/Mack.

One of the problems with the ATD part number is that in many cases, it is not possible to purchase them as complete devices. Instead, you need to buy the individual components. At Skyline, you can buy the DOC, the DPF, and the clamps and gaskets used to connect them.

In general, each ATD or ASM part number refers to a unique configuration of modules, so Skyline has started including an OEM assembly part number in our cross-reference lists when possible with the heading OEM Assembly #". When an assembly contains both a DOC and a DPF, the Skyline search engine will return both components. For example, 4387636 returns DOC XQ0461 and DPF XQ0710; 5294218 returns DOC CJ0430 and DPF LJ1206. Therefore, it is important to double-check which component you are looking for before placing an order.

If Skyline doesn't cross-reference your ATD or ASM part number, how can you find the part you need? Here are two possible solutions: 1) look closely at the parts, looking for the terms CATALYST or FILTER, 2) consult a dealer who works on the vehicle (Kenworth, International, etc.) for help in identifying the part number of the module you are looking for. You probably need a VIN for this.