Aftercooler Oil Cooler 3924731 For Cummins 6C 6CT 6CTA 8.3L Diesel Engine. Part Name: New Aftercooler Oil Cooler/p>. Engine Model: 6C 6CT 6CTA 8.3L. Fitment Type: Direct Replacement. For Cummins 6C 6CT 6CTA 8.3L Diesel Engine Parts. 1pcs Aftercooler Oil Cooler. Australia & New Zealand. During this period, we will be obliged to provide a brand new replacement for the quality issue you encounter. Feedback is very important to us. So that we can satisfactorily address your concerns.