40 HP Mariner/Yamaha year?

[fishook1976]

I just bought a 40hp Japanese made mariner, and i am not sure of the year. It has electric start, plus pull start, power tilt and trim. The numbers that i got off the nameplate are: Serial #503421, 6E9 L, & 40ELT0. I took the lower off b/c the drive shaft is froze up solid. i took the prop off, but I cannot get the nut off after the prop to see if there is any damage inside the lower unit! Can anyone help me please? Thanks!

Jason