can someone run a serial number for me and tell me information please

[bleedblue94]

hi, im looking at upgrading my motor and have found what the seller claims is a mid 80s merc 150. i got the serial number from him. can someone tell me the year, shaft length, and whether this motor (depending on the year) was prop rated or crank rated, and whatever other info can be deciphered from this? i have not seen the motor yet in person and it is a 2hr drive so if i do go to see it id like to have as much info as possible ahead of time!!!

serial number is: A181435

thanks everyone