Power Steering

Most likely a TRW Thompson Pump. Turns out there are two pumps that people like to call Federal. The first is the TRW Thompson which was replaced about 1970 with the Federal pump, which later was replaced by the Saginaw. The following page has a picture of the back side and some other differences listed: http://www.hoffmanswinnerscircle.com/cat16.htm From the front the quickest way to tell is that the TRW Thompson does not have a hole in the center of the shaft while the Federal does. Pulley diameters are usually about 5" for the TRW Thompson and 7" for the Federal. The TRW rebuilt units come with pulleys on them while the Federal does not and to my knowledge on March is making an aftermarket pulley at the present time to fit the Federal.