I've searched, and so far I've come up with the following conclusions: The A650e from the GS400 has a different valve body tune than the one in the 300 to manage the extra power. The 400 A650e will work fine in a 300, but the opposite may not be true. The shift position sensor is specific to the car it came from because some have PRNDM32L, some just have PRNDL, etc. The A650e was used in basically all V8-powered Lexus cars from 1998 to 2005-ish. The bellhousing bolt pattern is the same on all of those, and even if it isn’t, the bellhousing can be swapped. E-shift doesn’t matter because that is controlled by the ECU. No physical differences in the trans in this regard. What I'm wondering though is: Will an A650e from, say a 2003 LS430 work in my 98 GS400? I expect I'd have an easier time finding a low-mileage unit from a 4.3 car. I'm looking at building a more performance-oriented tranny using the accumulator shim method, and I don't think my original tranny is up to the task. It's got 204k on it, acts a little funny sometimes, and I'd rather just get a whole younger unit to mod and then install that. It'd be cheaper than replacing all the solenoids and rebuilding the clutches. Thanks in advance.