There are two different throw out bearings for the chevy, short and long. The short bearing is used on diaphragm clutches where the fingers are more uplifted and cone like (usually higher performance pressure plates) and the three finger pressure plates. the long bearing is used for stock diaphragm pressure plates where the fingers are flat. My assumption is that you have a stock flat fingered pressure plate so you want the long style.
As to usa made, I am not sure there is any in current manufacture but the last usa throw out bearings I purchased I found on ebay. BCA, Green, L&S, Delco of course, others.
