I posted on the end of another thread hoping to get some feedback as I'm looking to start this project within the week. But I think it makes sense to start a new thread as this is a project of it's own others may have interest in. I was surprised to not see that more people have done this since it seems like it's not too big of a job.

I recently bought a XF off of a past member. Car has 160k miles on it, the clutch is going and there is a slight knock at idle. I've already dropped the car at the mechanic to do a 3.7 swap. I have a new LUK clutch and I'm shopping for a motor to buy within the next week or so.

Any advice on buying the used motor? I'm looking for a motor with 100 miles or less, an 03-05 ML350 or 06 S350 engine. Preference over the two? It looks like the S350 is rated 241/258 HP/TQ compared to the ML at 232/254. I think as long as I get a used one with warranty that has been tested running and for compression I should be ok. I'm planning on changing all fluids, several seals,etc.

I told the guy who's doing the swap that it's pretty straightforward except for the mechanical fan. Is that correct? Anything else I should tell him?

Happy to answer any questions I learn as I go through the process.