I had the good fortune to stumble upon this thread and made an account just to post this. Obviously you're very knowledgeable about these engines so I'm hoping you (or anyone here!) can help me. I hope this isn't hijacking your thread too much but I figured others would benefit more if I posted here as opposed to sending a PM.
I have a G35 with nothing wrong with it except a bad motor (run into a deep puddle and sucked up water) along with a G37 that was t-boned driverside door and totaled but everything else is OK and the engine is immaculate. I wanted to swap the VQ37 into the G35 and figured it would work fine as the VQ37HR and VQ35HR have the same block, bore, etc.
I have only ever done maintenance stuff so I hired a mechanic known to a family member to do the swap. The mechanic, after removing the VQ37 said something similar to Doocam as far as the VVEL in the vq37 being different from the vq35. The mechanic told me he called an infiniti tech who said the swap was possible but that a lot more wiring labor would be necessary and that it would cost a lot. However, on the phone a guy I was considering purchasing a VQ35 from told me something similar to your response to Doocam - that as far as differences between 35/37 it would just plug in and my only issue would be fooling the ECU.
I can't be sure but I think the mechanic may have exaggerated or just made up what he was told by the tech because he didn't want to mess with the computer system at all. He said that pretty much verbatim actually, though his main argument for buying a VQ35 to put in and selling the VQ37 was that it would be maybe double the labor cost total for the VQ37. There are only a few VQ35's within a few hours drive of me, and the only other option is buying sight-unseen online via junkyard/JDM dealer/ebay which seems like a very unwise risk to take given the high shipping costs and the very limited warranty.
What is the real deal here? Is the added difficulty not nearly as significant as my mechanic is saying?
I'm going to call an infiniti dealer myself and try to get a tech on the phone and ask them too (not sure why I haven't done that yet...)
I'm extremely grateful for any info relating to this situation.