1993. Before the change to the engine mounted vacuum pump. My 2004 FG had the engine mounted pump as well.
Apparently car enthusiasts who hot their engines need an electric vacuum pump to make up for lost vacuum at an idle and some Ford trucks use an electric vacuum pump. But I haven't found one that produces the 18 - 22 inches of vacuum that the stock pump does.
Although if a Ford 650 uses an electric pump with 12-15 inches of vacuum I my FG should work okay with the same pump.
How many amps is your alternator without the pump on the back? Mine is 75-80 amps.