Semiconductors have advanced a lot in the last 50 years. Faster and much more efficient. What was hard to do 50 years ago is easy now. That is why you don’t need the mongo power transistors and heat sinks anymore like on on the old mopar boxes. They are fake on a lot of the new ones. Most of the heat in a semiconductor is generated during switching, not when it is on. Faster the switching the less heat Is generated. Less heat means they can be smaller.
If you are paying high dollar for an old mopar box, I would question whether you are getting anything better than a cheaper current design.
