[m5james]

The block itself should be completely the same, yes. My GF's 08 535xiT with the N54 started exhibiting knock, I changed the oil and it got better but never went away...ultimately the engine seized. After having taken apart the engine, it appears that injector 1 failed, flooding the engine to the point where eventually it hydrolocked itself. I got the engine from a 335i, which in my situation had a different oil pan (RWD vs AWD), AC compressor was clocked slightly different as well as it's fluid connections, and the wiring harness itself was different. I bought two Harbor Freight engine stands, put both on stands side by side and started comparing from there...but as I said, block to block, it was exactly the same connections, just a few different routings here and there. N54 only had one revisional change where it went from being an open water jacket to a closed water jacket under the heads, but you'd never know looking at it from the exterior and that doesn't affect swapability.

I had a HUGE and 1.5 month drug out shitshow of buying a used engine from www.car-part.com (not their fault) and a junkyard called G&N Auto Salvage (100% their fault, you can see my feedback on their Facebook page and just about anywhere I could leave an online review) where said junkyard lied about the mileage of the $1900 shipped engine had a claimed 70k mileage, but after further research actually had 167k. Verify via VIN, junkyard car pics, etc before purchasing an engine. Fortunately for me I was able to find a totaled car locally on the PNW BMW N54 Facebook page and got another engine for $2k w/ a confirmed 72k and the cars been back on the road w/o issue for over a month now.