ok little insight if i were to to remove my carburated engines out of my 1985 boat and want to put 1997 mpi 502's in will they plug and play or is there changes needed and thanks in advance

If you have the 10 pin connector already in the back, it will mostly be a plug and play deal as long as the motors are 100% complete.

Concur. The 10 pin is merely a transport for data from engine to helm, starter, ignition, tach readings, temp etc. The motors are virtually stand alone and ready to run as is. The EFI portion doesn't know or care what boat its in. I've seen a guy put a 350 EFI/Mag MP motor in a pickup.

So how did he hook up the shifter cables?

No shifter cables used and obviously non-marine exhaust.

was supposed to be funny...