Offered is a drop-in replacement for the 3978734CN Cummins Heat Exchanger. This product has a 5" Diameter and a LOA of 27". We manufacture this with a Copper nickel cooling bundle only. This increases the life of the heat exchanger as compared to one with a copper cooling bundle.

There is some confusion as to the proper part number for this part. We have it posted under both the proper part number 3978734CN and the incorrect part number 3978374CN so that those with incorrect data can still find their part. Part shipped will be 3978734CN.

This part is guaranteed for fit and function and is warrantied for 2 years in pleasure boat use.

Used on the following engines: SD4.5 CM2150,B5.9 LPG Plus CM556,G5.9,ISB 5.9 G CM2180,B4.5s,ISF3.8 CM2220 AN,ISB6.7 CM2250,B4.5 RGT,ISB CM800,QSB5.9-44 CM550,B5.9 G,G3.9,ISBe4 CM850,ISD6.7 CM2150,ISD6.7 CM2150 SN,QSB6.7 CM2250,QSB3.9-30 CM550,QSB5.9-30 CM550,B Gas Plus CM556,B6.7s,ISB CM2150,ISD4.5 CM2150 SN,ISB CM850,B LPG Plus CM556,B4.5,B3.9,ISF2.8 CM2220 AN,ISB6.7 CM2150 SN,QSB6.7 CM850,ISBe4 CM2150,G5.9 CM558,ISB6.7 CM2150 SQ,ISB4.5 CM2150 SN,ISB CM550,QSB5.9 CM850,B Gas International CM556,QSB4.5-30 CM550,ISBe CM800,ISBe5 CM2150 SN,QSB4.5 CM850,B5.9,ISBe CM850