Cat Conversion Harnesses - MAWK INDUSTRIES: CAT CAT ADAPTERS . Cat Conversion Harnesses $775 to $875 for most trucks 10 feet long. These harnesses are used to replace mechanical engines with electronic engines. Each wire is colored coded with eleven colors to match the Caterpillar wiring schematic. Each wire is printed every six inches identifying what circuit it is such as Check Cat Engine Wiring Harness for sale on HeavyTruckParts SEARCH - Cat Engine Wiring Harness. CAT 3406E ENGINE WIRING HARNESS, P/N 138-1011, 40 PIN : 877-238-5030 Request Info. EnterpriseVander Haags Inc Sp Spencer IA Looking for cores? Click here for core and unpriced items. Your search has 143 matches. Now showing results 1 through 25.