If you know the name of the lady he married, that will be of great help.
You can look up her name at the hall of records, local for that area, and find out what her married name became. As well as a record for the daughter being born. And the name of the daughter.
Salt lake city has a large data base that covers many different states, and I believe much of it is online. You may want to check into it. A lot of ppl use it to find long lost relatives.
Knowing the state to start with, and her maiden name are important. Knowing when she was married to your grandfather, and when she got remarried are helpful as well.
If you are unable to gain the info you want, then you may want to hire a private investigator, esp if this is not local.
If it is local, go to the libary first, they should have even the oldest of papers on micro film ( hopefully). It is a great way to find something without the hassle of the legal system to go thru.
Good luck.
"I will not live for power, I will not live for pleasure, I will not surrender the responsibility for my life or my actions." John Powell- on the three temptations of Christ
"Going to church doesn't make you a Christian any more then standing in a garage makes you a car".