I think they started adding an extra fuel pump into the tank in 85 (for the 86 model) or they may just do it for certain cars. When I went to Brumos to get a fuel pump, I was there for about an hour while they tried to figure out if my 86 300E had 1 or 2 fuel pumps. My car only has one though so I lucked out. Anyhow, I think you can find the build date in the drivers door frame.
1997 Acura Integra GS-R