Anybody ever done a 6.6 Duramax Swap into one of their trucks in Chev/GMC Posted June 20 · Edited June 20 by Knighthawk Towing there is a company here in the states called DMAXSWAP.COM that will take your Donor Harness, and remove all the excess wiring and make it the stand alone harness. they will also take your donor ecm and tune it to run just the engine. eliminating the factory gauges, security chip, emissions, ect to just run the engine. I don't need all the computerized Allison stuff because my Allison is completely mechanical. I have talked with several folks who have used this company and for the most part they are supposed to be pretty much plug and play. unless you are trying to do something weird like use the cruise control for throttle up, ect. when you get the harness and ECM back it has it's own fuse block, you hook up a constant hot, switched hot, and a ground. supposedly all the electronics on the engine will work and function as they are supposed to. they say the hardest part is the intercooler piping and hooking up your mechanical gauges. but I am still doing my research. like to be fully informed before I pull the trigger.