Hello all,

I am driving a 2010 Lexus LS460L with 163k miles. The transmission that is on this vehicle has been shifting a little off for a while, but I had always attributed it to the mileage I bought it at (153k miles). I had suspicions that it may have been flushed in the past. It is not until recently where I developed a leak where things have started to come up. The reverse in my transmission will not engage. I am considering swapping this one out for a JDM one because they are much better deals. I keep seeing people say that I would have to modify these to work. I am looking at pictures of the USDM and JDM transmissions and they don't look different to me. What exactly do they mean by modifications? Are there any significant differences between the two? Is it safe to use a JDM transmission? Will it drive okay if I don't get it programmed by the dealership right away?

A sub-question: If I use Lucas stop slip, could it help with my reverse? Initially it would clunk but would always engage. I think it burnt itself out when the fluid level got low, but I am thinking it doesn't have enough pressure to engage. If I am on a perfectly leveled strip of tar, I notice my reverse will move only a little bit. I cannot use the gas to push it for some reason. I had to add more new fluid since the transmission was leaking and I think it made it less viscous. Note, the filling was done at the dealership while I was getting my accumulator serviced. I am going to do the transmission work on my own since I have the ability and I do not want to be taxed.