Engine question
 

So I'm buying a 2004 Se maxima with a blown engine. Do I need a 6th gen engine for a replacement or will a 5th 3.5 work? Does it matter if it's an auto or m/t engine other people than flywheel parts witch I will alleeady have from blown engine. Any other things I might run in to that you can tell me? I'm going to change water pump and timing chain whel it's out of the car and put headers new flywheel and clutch kit whel it's apart. Any other cheap mods that I should do with the engine out? Thanks for advice. And this is not the first swap I've done just not on a fwd Nissan. And if I get 350z cams do they make much of a difference and how difficult is it to put in in cams with the engine inplace.

Do not know it a 5th gen engine will work. Would assume that it would.
I would replace the mount and transmission mounts. Expensive but much easier to do with the engine and transmission removed.
I would also replace the spark plugs and check the valve cover gaskets for leaks. To remove and replace the camshafts you have to remove the timing covers and camshaft chains. I you are going to change be sure and change when you replace the timing chains, tensioner/s and chain guides and shoes.

Yea my plan is new timing chain/ kit, new clutch new water pump, new spark plugs and herders. I just really want to know what vq35 engines will work with this with no wiring. Will the Altima 3.5 work 5 gen, ect.... And if it's an auto donor engine I just need to change the flex plate to a flywheel right?

I did an 06 swap into my 02 a few years back and it worked fine, i don't see why not ? The 02-03 has no EGR also, you will have to swap over oil pan and little stuff externally. If different drive train auto/manual u will have to swap out the throttle body if my memory is right.

So I'm gunna guess any vq35de will work for a new motor as long as it's fwd biased right? I found an 07 Altima 3.5 with 80k miles for cheap is there any differences between the motors. Is the cam duration and lobes shorter and smaller on some vq35s than others?