I have a 2005 GMC Yukon SLT 4wd. I am replacing the engine with a low mileage engine (5.3 LM7). I just bought the truck and the seller was dishonest and hid a ton of problems. This is my first LS platform and I am learning as I fix the many issues with this truck. I had done some research on the 4l60e and assumed that is what this truck had. It also has the RPO code M30. To my surprise, after getting the engine out, I noticed the center bolt hole associated with the 4l65E. Is there anyway this could have come stock? Or, did it have to be dropped in later in the life of the truck? The truck has 188k miles on it. I assume the trans will go sooner than later. I am hoping this was replaced in the last few years.