yamaha serial numbers

[ebluet1]

hi,new to this.. Im trying to find out the years of my to yamaha's.
50hp s/n 320218 and 70hp s/n 350602. The second problem i have is i am looking for a crank,rods and pistons for the 70 and told there like **** dust..
Can anyone help ! thanks

[boats.net]

What is the complete model numbers? That will tell the year.