There's a couple of ways to go here.What you really need in their WW2 service numbers, which is essential for getting any info from govt. sources.
See if anyone in the family saved any of their WW2 letters home.Their service number will appear in the return address portion.
Contact your local VA office.If your uncles ever applied for VA benefits, they'll have a record of it and be able to provide some information, including service number.
Check with the city clerk's office of the town they returned to after the war.Many vets filed their discharge papers with the town when they returned home.
If you're nearby in Iowa, visit their graves.Some vets have headstones or markers that will show military unit, rank, etc.
Once you have their service numbers, you can write to the National Personnel Records Center in St. Louis for their records.See message #2112 on this board.
Having said that, all you will usually find out is rank, date of induction, date of discharge, awards/medals, and unit.Remember, there will millions of men and women who served in the armed forces during the war, and the govt didn't keep detailed records of what each soldier did on a day to day basis.Once you have a unit for each uncle you can trace a history of the unit, what battles they were involved in, etc., but specific info on your uncles might be hard to come by.