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The D6D’s Place in Caterpillar’s History
The Caterpillar D6D bulldozer was introduced in the mid-1970s as part of the D6 series, which has long been a cornerstone of Caterpillar’s track-type tractor lineup. Known for its balance of power, maneuverability, and reliability, the D6D was widely used in construction, agriculture, forestry, and land reclamation. Powered by the 3306 diesel engine, the D6D offered around 140 net horsepower and featured mechanical controls, a torque converter drive, and optional low ground pressure (LGP) configurations. Caterpillar, founded in 1925, had by the 1980s delivered hundreds of thousands of D-series dozers globally, with the D6D remaining in service decades after production ended.
Serial Number Plate Damage and Identification Challenges
When a machine’s serial number plate is partially missing or corroded, identifying the correct build year and configuration becomes difficult—especially when ordering parts like LGP tracks. In one case, the visible portion of the plate read D6D 20X789, with the engine marked as 3306 49V13295. The right end of the plate was broken off, raising concerns about whether the serial was complete.
Decoding the Serial Number Format
Caterpillar serial numbers typically follow a prefix-number format:
Engine Serial Number Cross-Reference
The engine serial 49V13295 belongs to the 3306 series, which was commonly paired with D6D tractors. Cross-referencing this number with Caterpillar’s internal systems confirms compatibility with D6D units in the 20X1 to 20X3041 range, reinforcing the identification of the machine as a 1977 build.
Terminology Clarification
When ordering aftermarket components like LGP tracks, suppliers often require the full serial number to match specifications. However, in cases where the prefix and production number are intact, and the build year is confirmed, most reputable distributors can proceed with the order. It’s advisable to:
Field Restoration and Operator Experience
One owner refurbished a D6D from near inoperable condition to full functionality using local mechanics and incremental repairs. After installing standard-width tracks for upland use, he planned to fit new LGP tracks for fish pond excavation in muddy terrain. The machine’s British origin added confidence, recalling the durability of UK-built tractors like the Massey Ferguson 135, which had served his family for decades.
Conclusion
Even with a damaged serial number plate, a Caterpillar D6D can be accurately identified using prefix logic, engine serial cross-referencing, and production records. For parts ordering and restoration, confirming the build year and configuration is often sufficient. The resilience of these machines—and the ingenuity of their owners—ensures that even decades-old dozers can return to productive service with the right support and documentation.
The Caterpillar D6D bulldozer was introduced in the mid-1970s as part of the D6 series, which has long been a cornerstone of Caterpillar’s track-type tractor lineup. Known for its balance of power, maneuverability, and reliability, the D6D was widely used in construction, agriculture, forestry, and land reclamation. Powered by the 3306 diesel engine, the D6D offered around 140 net horsepower and featured mechanical controls, a torque converter drive, and optional low ground pressure (LGP) configurations. Caterpillar, founded in 1925, had by the 1980s delivered hundreds of thousands of D-series dozers globally, with the D6D remaining in service decades after production ended.
Serial Number Plate Damage and Identification Challenges
When a machine’s serial number plate is partially missing or corroded, identifying the correct build year and configuration becomes difficult—especially when ordering parts like LGP tracks. In one case, the visible portion of the plate read D6D 20X789, with the engine marked as 3306 49V13295. The right end of the plate was broken off, raising concerns about whether the serial was complete.
Decoding the Serial Number Format
Caterpillar serial numbers typically follow a prefix-number format:
- Prefix: Indicates model and factory (e.g., 20X for D6D units built in the UK)
- Number: Sequential production number
Engine Serial Number Cross-Reference
The engine serial 49V13295 belongs to the 3306 series, which was commonly paired with D6D tractors. Cross-referencing this number with Caterpillar’s internal systems confirms compatibility with D6D units in the 20X1 to 20X3041 range, reinforcing the identification of the machine as a 1977 build.
Terminology Clarification
- LGP (Low Ground Pressure): A track configuration with wider pads for better flotation on soft terrain.
- 3306 Engine: A naturally aspirated inline-six diesel engine used in various Caterpillar machines.
- Serial Prefix: A code indicating model type and manufacturing location.
- Aftermarket Tracks: Replacement track assemblies not manufactured by the original OEM but designed to meet or exceed specifications.
When ordering aftermarket components like LGP tracks, suppliers often require the full serial number to match specifications. However, in cases where the prefix and production number are intact, and the build year is confirmed, most reputable distributors can proceed with the order. It’s advisable to:
- Provide engine serial number as secondary confirmation
- Include photos of undercarriage and track frame to verify configuration
- Confirm track gauge and pad width manually before placing the order
Field Restoration and Operator Experience
One owner refurbished a D6D from near inoperable condition to full functionality using local mechanics and incremental repairs. After installing standard-width tracks for upland use, he planned to fit new LGP tracks for fish pond excavation in muddy terrain. The machine’s British origin added confidence, recalling the durability of UK-built tractors like the Massey Ferguson 135, which had served his family for decades.
Conclusion
Even with a damaged serial number plate, a Caterpillar D6D can be accurately identified using prefix logic, engine serial cross-referencing, and production records. For parts ordering and restoration, confirming the build year and configuration is often sufficient. The resilience of these machines—and the ingenuity of their owners—ensures that even decades-old dozers can return to productive service with the right support and documentation.
