i did go see a performance shop and they tell me i have to stick to 7.5 that 8.8 wont fit my car so thats why i asked what i would need to make it fit but thanks anyways ill just get the 7.5 im doing stripes on it tomorrow and hopefully new gears in 2 or 3 weeks when i get them

Are you serious!!The 8.8 is a direct swap.The difference between the 7.5,and 8.8 is the centre section in size.The rest is exactly the same!!!!!!!!Well minus small details like brakes,and axle lengths threw the different model years,but as long as you stick with the '99 to '04 8.8 diff,everything from your 7.5 will swap right onto it,and the 8.8 will bolt right up to your chassis.I know,i've done this swap on an '85 GT that is equipped with a 7.5 from the factory,i went to a 8.8.
Here is a couple of pics to show you the only real difference....
7.5 centre section bolt pattern/diff size
http://farm4.static.flickr.com/3565/...21930d50_o.jpg
8.8 centre section bolt pattern/diff size
http://farm4.static.flickr.com/3627/...30418949_o.jpg

k so i dont need any extras then?and like will i need 31 spline instead of 28?

Any upgrade will be up to you.If you plan on big hp,and torque,yeah upgrading the axles,and the limited slip is a good idea.
I myself with my '03 GT,all i did,being on a budget was upgrade the axles,but kept them with the stock 28 splines,along with my gear swap.So far it's been good...(knocks on wood!)
But basically,any extras will be up to you.
You can upgrade the upper,and lower trailing arms,shocks,springs,iscolators,brakes,limited slip diff,axles,gears,add a panhard bar,diff girdle cover,ects......That will be all up to you.
Now if you are doing this under a budget,a 8.8 will bolt right in,and you can swap in the gears of your choice,and you will be find with just that.Then later on you can upgrade the rest as you can afford without ripping a hole in your pocket.

ok tyvm u guys are all so nice

We try our best to help the new guys and dummies like me being an old guy tehehehe

Your never too old to learn!!:tup

The old expression about teaching an old dog new tricks, that's me

Classic case of Age and Wisdom vs Youth and Enthusiasm.

LMFAO .... This thread is def. taking a turn now!!!