what is my rear end?
 

I was thinking of changing converting to ford racing performance limited slip differential for my 98 Mustang Gt Convertible. I dont know what my exact specifications are for my back end. Is my stock 98 rear end 8.8 inch and 31 spline?

If you are 5spd then you prob have a 2.73 in your car, you could also have a 3.08/3.27, it depends on whether or not the person before you ordered the lower gear... If you have auto then most likely you are 3L08.. The easiest way to tell is to look on the pumpkin of the rear end, on the cover you will see a silver metal tag. This tag will have a number combo like this:

308 = 3.08
273 = 2.73
3L08 = 3.08 Trac-Lok
3L27 = 3.27 Trac-Lok

etc... that's your gear ratio

Yea, stock I have 2.73 gears...but thats not really my problem. I need to know if I have 8.8" 31 spline rear end or if i have like a 7.45' 28 spline rear end.

Sorry, was in a hurry earlier when I read that. You should have an 8.8" 28 spline axle, not 100% sure about splines, but I know you do have 8.8" rear.