Seakamp 212144 Marine Oil Cooler 2"x12" Body 1/2" NPT and 1-1/4" Hose
The Cummins' transmission oil cooler doesn't have a zinc and is subject to corrosion. Nellie's had corroded badly (I could see daylight through the metal) under the the raw-water hose attachment point. It's a good idea to visually inspect the exchanger every three to five years.
Replacement exchangers are available from Fredwarner1.com for $110.09 (March 2018).