trans oil cooler
I have an 88 825SL Sterling that uses the 2.5 V6 and G4 Auto transmission.
When the trans oil cooler in the radiator failed about 4 years ago I just used an aftermarket external tramsission oil cooler.
I purchsed it at Pepboys and mounted it in front of the A/C condensor and radiator using the plastic fastners provided.
It worked fine until I had to replace the radiator due to a leak.
So the only tricky thing is to figure out how to mount the oil cooler in the front of the radiaotor/A/C condensor.
Hope this helps,