Detroit 12.7L Series 60 Connecting Rods

Nu-Line Heavy Duty – Bulletin No. NHD-DD1.60-01, Group No. 1.60

October 29, 2012

Nu-Line Heavy Duty is please to announce the availability of connecting rod 123526078 for Detroit Series 60 12.7L engines. This closed-end connecting rod is used with the forged steel piston and 85 mm crankshaft rod journal. Casting number of the connecting rod is 23525604.

Part number 123526078 is the later design with drilled oil passage through the rod to lubricate the pin bushing. Drilled rods were utilized in production from model year 2000 until the EGR introduction in 2004. This connecting rod can also replace the former non-drilled connecting rod in earlier eninges.

Conversion from iron to steel pistons:

Engines produced with cast iron pistons (bolt-on to connecting rod) and engine serial number above 06R0408505 may be converted. These cylinder blocks can accept a steel piston configuration along with the closed-end rod. Please contact [our team] for details on upgrading from original iron pistons with bolt-on rods.

Nu-Line Heavy Duty supplies a steel piston replacement option for failed engines that have iron pistons. The cylinder block must have production piston cooling nozzle machining. The steel piston utilizes a closed end connecting rod, which is also available from Nu-Line.

The following information lists production changes to the block and pistons.

Serial NumberDate of ChangeChange Description
06R0408505Approx. 02 March 1998Piston cooling nozzle machining added to all Series 60 cylinder blocks.
06R041164916 March 1998New steel piston and connecting rod used in all Series 60 12.7L premium
engines (PK). Corresponding new parts released include piston skirt,
piston pin, retainer clips, and block-mounted piston cooling nozzles.
06R0512310Approx. 01 June 1999All 12.7L standard engines changed to steel pistons with corresponding

The above engines can be converted to the steel piston (except 12.7L Premium). Connecting rods will need to be changed to the closed end style with drilled oil passage. Piston cooling nozzles must be used with new piston and rods. Select the steel piston with the compression ratio to match your engine (15.0:1 or 16.5:1).

NOTE: Nu-Line Heavy Duty does not recommend the use of the Nu-Line iron pistons for the 12.7L Premium (PK) Series 60 engines with serial number 06R0408505 or later.


Jimmy Finch

Dallas Branch Manager, M&D Distributors

Jimmy Finch has over 33 years of experience in Diesel Engine Sales, Service and Repair. His experience started early in life at Texas Fuel Injection Service (an early acquisition of M&D) as a job with a means to an end. Somewhere in that 33 years this job turned into a fulfilling career. He started in the injector clean up department and has held practically every position leading up to his current role as Branch Manager of the Dallas, Texas location.

In his spare time, Jimmy enjoys spending time with his wife of 24 years, Priscilla. They are currently getting ready to make their way into the empty-nesters stage of life. He also enjoys the occasional hunting trip with friends and family and chasing down potential customers by the names off their trucks.

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