88 mustang lx rear end?

hi i was wandering what size rear end i have in my 88 lx non hatch? i think it might be an 8.8 but not to sure just wanna make sure b4 i but my 7.3 gears it use to be a 4 banger but now i got a 89 5.0 and wanted to know what i should buy to beef it up. I am already ordering headers not sure which to get short or long tube. I am also ordering my 7.4 gears and a posi traction locker. what else should i get to soup it up a little funds are not too great right now but i got some play money to put into her. thanks alot