I am doing some work on my family tree, and need some help?

[diane_p]

My grandfather and grandmother did not have their first child until my grandfather was 43, and I recently found out my grandmother had a whole other family we knew nothing about..so I am betting my grandfather did as well. How can I trace my grandfather and found out who he was married to before my grandma, what kids he had, that sort of thing. At this point I am not sure him and my grandmother were even married. Any advice? I want to find his other children, and I really believe they are out there. His name was Allen Mason Murray, dob is 10-05-1905, and date of death is 1-27-1974, in Pueblo, CO. I know he was born in Missouri, but his social security number was isued in Arkansas I believe, and have no idea what states he was in during the years that are unaccounted for. My grandmothers name is Thelma Maxine Crawford, and is still living. Can anyone help me? Thank you so much.