How and where to measure shaft length on MK trolling motors

Title says it. I am looking for a new TM and want to make sure I get the right length. I figured I would measure my old one.

Also I saw in BPS new catalog today that MK offers a 45 in length terrova now.

Thanks
Clint

From where the shaft enters the head and motor and add an 1in.

Thanks wilbur. I wasnt sure if I need to add the motor and head or not.

Thanks again
Clint