Trying to id outboards

[Grant 72]

Hi I recently purchased two 30hp 2 stroke outboards. The covers have Mariner on them but the actual outboards have the Yamaha logo on them followed by Y-1 68900.
I am looking for the year and model.
I also need to know what the serial numbers are for the insurance company.
Not sure if these are the s/n but found these numbers 408336 and 408342 on small discs on the power heads.
I am based in South Africa
.

[boscoe99]

The numbers that you found appear to be the serial numbers. I presume the disks that you are talking about are black round decals with a white bar through the middle. And in the middle of the white bar are the numbers in black.

[JohnOrrett]

That serial number range seems to indicate a model 30AE Longshaft from 1983