I believe the fox body rear ends are going to be too narrow for your setup. You will want to go with a 94-98 rear end instead.
As far as figuring out what gears you have now...who knows. If they've been replaced really the only way to tell would be pull the cover off and count the teeth.
"I'm not driving too fast...just flying too low"
-03 SB Cobra vert- 2552 of 5082 Born 02/25/03
90 7up vert - new project-07 DSG Focus -DD