My great grandfather was in that battalion during WWII, I don't know a lot about it since he never really talked and I don't personally have access to his stuff. I only know that they were among the first to land on Utah beach during Operation Overlord (D-day) and were attached to Patton's tank unit during the liberation of Buchenwald.
Would providing my great grandfathers name help in any way?
I am not able to give you too much, but here's a list of signal units in the normandy campaign. http://www.ibiblio.org/cizewski/signalcorps/normsigunits.html
The 433rd is listed as a "signal construction battalion." Which might help clarify. Did you try pulling his records from the government itself? You may want to double check the battalion number too.
If you have some personal info I think you can request his military record here: http://www.archives.gov/veterans/military-service-records/standard-form-180.html
Also, this is slightly goofy, but there is a reenactor website that seems to have a pretty good idea what exactly a Signal Construction Battalion did in world war two, which is otherwise a fairly obscure topic. http://www.33rdsignal.com/