Fuel Pump
 

I have a 72 240Z with after market A/C. My mech fuel pump went out. I am trying to replace the pump. I ordered a new fuel pump from Vic\Brit. It is a Beck/Arnley 151-5725. I had to take the bracket that holds the A/C compressor to the block to get access to the bolts, etc. After I got the old off, I went to install the new pump. Had to remove the studs as there wasn't room with the A/C bracket. I put the pump in but the bottom doesn't mate up to the block. What's wrong. I took the old one and slipped it into the hole and it mates up to the block. Do I have the wrong pump? Is there something else I am doing wrong? Sorry for the long email but, I need HELP!!!!