ECM Controllers & Monitors

366-8821 Electronic Control Group for CAT 320D 324D 330D

Q: What numbers are documented for 366-8821?

Primary Part Number: 366-8821. Physical Label Identifier: 366-8821-00. Official Reman Alternate: 20R-2323. Related Discontinued Control Group - Verify: 221-8874. Formatted Alias: 3668821. Relationship labels distinguish formatting aliases, direct interchanges, remanufactured references and related assemblies.

Q: How do I confirm 366-8821 before ordering?

Match the complete part number, compare the connector or mounting arrangement with the product photos, and confirm the machine or engine model and serial range. Send clear photos of the original unit when requesting a quote.

366-8821 Electronic Control Group for CAT 320D 324D 330D, OEM/reference 366-8821, Electronic Control Group, product view 1

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OEM / reference366-8821

SpecificationElectronic Control Group

Catalog ID51134098

Electronic control group identified by CAT part number 366-8821 and the exact 366-8821-00 label visible in the owned physical gallery. CAT states that the unit is shipped without software and lists 320D, 324D, 330D and many related D-series applications. CAT lists 20R-2323 as a remanufactured alternate. The discontinued 221-8874 control group is retained only as a related legacy number requiring serial, connector and software verification.

Product Type: Electronic control group / ECM
Housing: Steel controller housing
Software: Shipped with no software installed
Connector Layout: Dual multi-pin connectors; compare exact keys and pins
Condition: New replacement control group; programming required

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Send the machine model, engine model or nameplate photo so our team can confirm compatibility before shipment.

Part-number relationships

Relationship	Reference family	Number
Primary Part Number	CAT electronic control group	366-8821
Physical Label Identifier	Exact number printed on owned controller	366-8821-00
Official Reman Alternate	Alternate displayed by CAT	20R-2323
Related Discontinued Control Group - Verify	Separate CAT control group; not asserted as direct replacement	221-8874
Formatted Alias	Same primary number without separator	3668821

Product fitment guide

Part numbers and compatible models

Quickly compare the reference number and recorded machine applications. Use the original photos and the checklist before ordering.

Part identification

Reference numbers

Primary number

366-8821

Formatting alias

3668821

Remanufactured number

20R-2323

Related assembly

221-8874

Other documented relationship

366-8821-00

Formatting aliases are the same number written differently. Related assemblies and remanufactured numbers are not presented as direct interchanges.

Product summary

Electronic Control Group

Category: ECM Controllers & Monitors
Catalog ID: 51134098
Photo views: 5

Before ordering

Confirm these details

Match the complete part number on the original component label.
Compare the front layout and visible configuration with the product photos.
Compare connector count, connector shape and keying before installation.
Confirm the exact machine model and serial range before ordering.

Machine fitment

Compatible model references

3 model references

CAT excavator examples: 311D LRR / 312D / 320D / 323D / 324D / 325D / 329D / 330D / 336D / 345D
Additional official families: 307D / 308D / M325D / M330D and selected mobile hydraulic units
Fitment limitation: Confirm 366-8821, machine serial, connectors and required software/calibration

Compatibility lists identify searchable model families, not every production serial range. Confirm the original part number and machine serial number before purchase.

Quick fitment answers

Common questions about 366-8821

Which machines use 366-8821?

Recorded compatible model references include CAT excavator examples: 311D LRR / 312D / 320D / 323D / 324D / 325D / 329D / 330D / 336D / 345D, Additional official families: 307D / 308D / M325D / M330D and selected mobile hydraulic units, Fitment limitation: Confirm 366-8821, machine serial, connectors and required software/calibration. Confirm the complete part number and machine serial range before ordering.

What numbers are documented for 366-8821?

Formatting aliases for the same number: 3668821. Remanufactured references: 20R-2323. Related assembly numbers (not direct interchanges): 221-8874.

How do I confirm 366-8821 before ordering?

Match the complete part number on the original component label. Compare the front layout and visible configuration with the product photos. Compare connector count, connector shape and keying before installation. Send clear photos of the original unit and connector layout when requesting a quote.

Continue comparing verified references from the same system.

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