Add new question to the seller

I was wondering how you know it's a 1970 boat? Reason I am asking is because we have a blue one identical to this one with no id except for the same weight capacity tag and the shell lake boat company tag, (and a 5 digit number plate), like the one you are selling. My dad is trying to get info on his boat so he can register it. I've looked online and I can't find anything as far as year and model based on the measurements and tags. The actual 1970 314 sportsman model boat has a different weight capacity of 657lbs not 575 and only a 20hp motor not 30hp rating,(not like the tags in both of our boats), according to the shell lake boat company records found at the following website link http://www.fiberglassics.com/library/images/7/7a/Shelllakebb006.jpg.
Anyway I would greatly appreciate any information you can give me. I've been very unsuccessful at finding anything online about these boats and was excited to see someone else who actually had one identical to the one we have. I greatly appreciate your help and time with this and look forward to hearing back from you soon.

Kind regards,

Tsali