New 4l60e combability with older ECM

hello, i am trying to help a buddy, he has a 2000 5.3 swapped into his rig with red blue computer. The transmission is a 2011 4l60e from express van, it plugged in & its shifting 1-2-3 at high RPM, and doesnt down shift back to first unless you turn it off. the codes trans codes were pressure control related so he bought the manifold pressure switch based on the codes and googleing. pulls the pan and there isnt one. not like its missing, but like it wasnt there from factory. is this newer transmission compatible with his older ECU? i know they have gone over some revisions over the years. but not sure of the interchange. thanks

I'm not a 4L60e guru but I know for sure that the connector plugs changed more than once over the years so the electronics are not the same.

https://www.silveradosierra.com/tran...e-t699690.html

That thread should help you.

He needs one with a 13 pin round plug. 2011 trans should have 17 pins.