Kent,
If the NPRC still has your father's complete personnel file, it will most certainly answer any questions you may have about his service. Don't know if you have read on the website about the infamous fire of July 1973 that occurred there. Roughly 85% of all the Army and Army Air Forces personnel files stored there at the time were destroyed. Not to discourage you, just be prepared that they may not have anything left of your father's file. You definitely should try though,some files survived intact and pieces of some files were recovered. The only thing they had on my grandfather's file was a copy of his final pay voucher, it wasn't much but was still pretty cool to have.
Randy
Ah remember, there are other places that can provide the info that NARA in St Louis had.
http://www.6thcorpscombatengineers.com/engforum/index.php?showtopic=23
Just want to make sure that peeps know they have other options.
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"