Effective with engine serial numbers 3D-170958, 4D-181763 and 6D-187523, turbocharged engines use a 1.500" diameter piston pin. With the use of the 1.500" diameter piston pin, new piston assemblies, piston pin retainers and connecting rod assemblies are required. The former piston pin diameter is 1.375". The former and new piston and connecting rod assemblies differ only in that they have larger bushing bores to facilitate the installation of the new, larger diameter bushings. the larger bushing inner diameter is necessary to accommodate the new, larger piston pin.
Because of the larger pin diameter, former and new parts are not separately interchangeable. When it becomes necessary to replace any one of the of the three major cylinder components, it will be necessary to include the other two to assure interchangeability.
Current piston assemblies and connecting rods can be mixed in an engine with the former piston assemblies and connecting rods.
Important! To be sure, we recommend disassembling the engine and measuring the OD of the piston pin other than relying on the engine serial number.
A lot of older engines have already been updated!