Ok im mainly a motor guy dont really know to much about drivtrains.But what i wanna know is im looking to get a another thunderbird its a 84 and i was woundering like how hard would it be to change out the gears in the rearend. And what would be the best ones to get.The car well see a little highway but mostly street and im looking to get a little faster take off from a dead stop, The car doesent have a motor but it had a 5.0 in it with aod if that helps out any
84 you prolly have the 7.5 rear I changed my own gears and it was rather easy took me less than and hour. If you can find an 86 Ford ranger they come stock with a 3.45 gears that will work in your 7.5 rear. Will give you a noticeable difference over the 2.73's you have now yet keep you on the highway without breaking the bank. I'll sit down later when i get time and write up the procudures for changing the rear gears but like i said it pretty easy.
Your best bet is to find a complete 8.8 rear out of an '86-'93 'Stang, either GT of 5.0 LX. This will improve durability greatly, give you more tire clearance and often times, the later models came with 3.27 gears. I have a whole outline of the procedure in my website in my sig. Good luck.
-Don
But would it fit on the 83?
yes, it will
direct bolt in , stronger rear end , strong following so aftermarket parts are easily avalible.
i would suggest a 3.73-4.10 with an aod transmission for mild performance use.
3.45-3.55 with a c-4 or other 3 spd auto
The 8.8 is going to be your more reliable rearend but to be honest if your only going for 200 hp your prolly going to waste alot of time and money installing it. My 7.5 (for the time being is handleing my 420 FHp just fine. Although i am upgrading this summer to a 9". Depends what your going to ultimately use the car for. dont think the 7.5 is going to fail you for changing gears. If you plan on modding to get more HP and torque definately look at the 8.8 or a 9 but being you have already stated staying at 200-220 i would leave the 7.5 in there.