1986 Yamaha 30 lower unit question
 

I have a 1986 Yamaha 30 that the lower unit is shot.i did get the cavitation plates that were broken welded back on and it looks nice.
I've gotten a few quotes to rebuild it and they were $900+

I've located a running 1986 Yamaha 40 that the lower is good for a lot less. He's asking $350 and he says it's a good unit.

My question will the 40 lower work on my 30?