Can I put an automatic transmission from a 2000 3.0 maxima into my 2010 3.5 maxima

 

No

 

do you know why or is it just a thing that's not been heard of much

 

It can p be done if you can make the Engine ECU talk to a different Trans computer. Plenty of wiring that might be possible to do! TPS, Engine RPM, Wheel Speed sensors is what I remember links the 2 systems together.

 

The best Option is just doing a 6 speed swap....

 

having CVT issues?

 

As long as it bolts on mechanically and there's no issues there, electronically it theoretically would be possible. I did it with my Crown and it has a Haltech 2500 PCM running both the engine as well as the different automatic transmission with a custom wiring harness to make it all work. But sometimes its not feasible $$ wise as the Haltech with custom wiring etc was like $4k CAD alone for me.

As others have said, 6spd swap has been done before and if you're okay with manual it'll be easier as it's a more mechanic transmission compared to dealing with the electronics of AT