I thought It would make for fun and unique scenario,long cargo hauling foreign train.Possibly and also to show DTG that you can couple and mixing locos do work without breaking the game lol.Yes surprisingly It does work,I've tested 40x It also works for ac4400cw but coupling class 66 to sd40 does break the class 66.Beware Platform : ps4_pro
It should work as they are both compatible with AAR multiple working. Basically they have the same power train, except the class 66 has the later 710 power unit and the GP38 has the 645. It does make you wonder how the squeezed the same unit into the UK loading gauge.
They had to make a lot of changes to the design to get it onto our loading gauge, most notably is the omission of dynamic braking and the deafening noise in the cab (which is why drivers hate them and makes the loss of the Class 60s more tragic).
I like the 60 as I do most UK stuff, But you cant get away from the superior nature of the EMD product we also didn't take up the whisper cab. Dynamic brake wasn't really needed in the UK. But we got "Radial bogies" , Reliability across the board In general compared to the Reliability of any BR built product. The main problem fitting US equipment into the British loading gauge was was no worse than the Western region fitting German stuff into the UK gauge. With US stuff it was down to the Cooler group. But EMD had solved that by the mid 1980s. The problem now is fitting the post 710 Emission compliant power unit into the UK gauge. Its not a major issue.