Irwin 28 built in the 70s

Jan 23, 2015
catalina catalina22 Trailer
Hello everyone, does any Irwin owners know where I can find info on a Irwin 28 possibly mid 70s. I want to know what keel design and what years they have changed. the boat is in the water and the inherited owner cant give me a answer he is not sure. Can anyone tell me what keel designs and what years they have changed and related to which models. Thank you Don