Try Numrich Arms at http://www.gunpartscorp.com/
I've had a lot of success with obtaining parts for older guns from them.
They claim to be the biggest gun parts dealer in the world. If you don't see the part listed or it's out of stock, call Numrich and speak to one of their reps. A lot of guns like the Springfield were made with parts that were common to other manufacturers and were identical matches. I found their prices to be very reasonable. Good luck with your search.
All that is necessary for the triumph of evil is that good men do nothing. Edmund Burke