Just wondering exactly where this little item is i have an aftermarket replacement coming and im not sure where it is even located can someone help me out

under hood, passenger side, under the coolant resevoir. pull the computer out and flip it over, there will be a gray square at the bottom with a couple screws holding it on. remove that. the chip will be directly under it. I'm assuming you ordered a piggy back. pull the old chip out, mount it on the top right side of the new chip, then reinstall.
BUT, double check with who you ordered the chip from to ensure it is the right one for your car. I ordered one thru superchips and they sent me one for a 95 s10, not the 92 z34. had to send it back. make the call and make sure...