C6.4 Engine Wiring Harness 296-4617 for CAT 320D Excavator Engine wiring harness 296-4617 / 520-7000 for the CAT C6.4 and 3066 engine in 320D, 320D GC, 320D FM, 320DL, 321D LCR and 323D excavators. Plug-in replacement using OEM-style connectors with no cutting or splicing required. Key Features Engine wiring harness for the CAT C6.4 / 3066 diesel engine OEM number 296-4617; replacement number 520-7000 / CA5207000 Fits 320D, 320D GC, 320D FM, 320DL, 321D LCR and 323D series