Ah sounds like we are in the same boat. My mom just passed away in January, and as my girlfriend says, I am now an orphan. Yes, a very strange feeling in life. Once in a while I catch myself saying something like, I should call mom today...
You still have many options open to you as far as getting more info on your father and his unit. Please check out the Research and Reference section in the forum. Here's the direct link:
http://www.6thcorpscombatengineers.com/eng...hp?showtopic=23
I would contact the Army Corps of Engineers first. Michael Brodhead is the head of the history department and was a big help to me when I first began my research. Their department has info on MOST units. I cannot guarantee they will have anything on the 501st, but it's a great place to begin.
Secondly you can contact Richard Horrell of WW2 Connections. He is a private researcher and has over 5000 books in his collection. He has provided help for many of my visitors.
You can contact NARA in Maryland too. This is something I did beginning last year. I hired a researcher (they have a list of names on their site) and she copied all the records for my dad's unit and mailed them to me.
You have to write to them first to determine if they have any records on his unit. From there you have three choices if you get a positive response. One, go there yourself and copy the records. Two, if there are only a few records, NARA will copy and send them to you. Three, hire a professional researcher or college research assistant to copy the records for you. Note: This is not cheap, but it was well worth it for me in the long run.
I'll be happy to assist should you have any questions while trying to pursue this. I've gone down virtually every avenue in 2 and 1/2 years and done a lot of stumbling, but then you find that one piece of info and everything starts falling into place. It's such a fantastic high when you do. You'll feel very connected to your father. It's almost like they are sitting in the room with you and rooting you on...
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"