Both the Orange and Chrome ECU's utilize the 793266 power switching transistors.

The difference between the two is in the support circuitry hidden beneath the potting material.

Yes, they get hot. That's why Ma Mopar installed ECU "standoffs" on some models. My old Mirada ECU was mounted directly on the fender apron, and I burned through one or two stock ECu's. The orange box on our old Monaco got hot enough to melt the potting material, and it dripped down the firewall.

After reading this post, and having just gone for a cruise in the 'cuda, I verified that , yes, the transistor gets a bit hot.

But that's why the CPU on your computer right now has a cooling fan - millions of transistors, switching current. Except those transistors on the CPU are tiny, and the ECU transistors are big 70's Godzillas.