Where is the inline fuel pump located on a 1988 ford ranger 2.3 liter 2wheel drive how hard is it to change?

I'mworking on a 1987 Ranger. The questions asked are; 2 or 4 wd, super cab or reg., rear tank or center tank. Mine is a 2whd,reg. cab, with a center tank, and today I found out I have two (2)fuel pnmps. One inthe tank and one on the frame rail just below the drivers side floor board. I have not yet been able to do a fuel pressure test but I have confirmed that both pumps do run. Neither pump seems to be to difficult to change. The one in the tank will be time consumming but do able. My present consuren is if I do a pressure check and it is low how do I deterrmine which is not up to par? Good luck with your truck and wish me the same.