Has anybody swapped a Heath ECM from one truck to another? I found a used one for sale a while back and called hDP to ask about having it upgraded from the HP4 to the GLE. Bill told me that it may or may not work with my truck as-is, and the only way to know it to try it. He said that there wasn't any discount for upgrading an older program to a newer one. He said that the ECM was just a good core as far as he was concerned and I should look at it the same way. I know that Bill's a good guy and I wish I had the coin to just order a new tune from him. But fact of the matter is, I'm poor, and cheap to boot!! I wondered if anyone had actually tried swapping ECM's and if anyone had actual experience with them working or not working. Thanks for your input.