ancestry.com has a great many military records, but it is a pay site. If you have some basic information, you can order their military records. Do a search engine "request for military records". There is a sight where you can download and print the forms, along with addresses. Bear in mind that many WWII records were destroyed in a fire, and have been "reconstructed" as best possible using whatever info is available.
If you know their units, you can use a search engine for that as well. Many of the old units have websites where surviving members can correspond.
Also check to see if you have a genealogy research center at your local library or archives. They usually can help track down the records you seek.
I was able to order the military records for my g-g-grandfather, who was a confederate during the civil war. I was amazed at the amount of records I rec'd.
Best of luck,
Ben