thank you for the reply. i'm stoked because he only wants 50 bucks for them. i wasn't sure because of the irs in the cobra. also is there anything else i need for the install?
Pick up some shims, and of course your fluids and friction modifier. Also some patience if they sell it anywhere, you'll need it unless you have done it a few times. Speedo gear if you want speedo to work properly.
If you've got a lot of miles, then you may want to have your traction-loc rebuilt while your at it. I got mine rebuilt a couple months ago, because of the humming noise that began.
3.55s are great highway gears, but you will definitely want a 23 tooth gear or a speedcal. I went with the 23 tooth and it is too close to tell if it is off. You didn't say if you had a 5-speed, but I'm guessing so.
If you have a shop do the install, make sure you use one that is reputable. Maybe ask fellow stangers around your area. I got my gears in and they never made a sound at all........of course, however, they were installed by one of Dugan Racings former lead mechanics. Nothing but quality work there, plenty of knowledge, and inexpensive.
Mustangs Unlimited and others sell some sort of Kit that includes several more replacement parts for the gear install. Might want to check into that also.