I want to apologize ahead of time since im sure this question has been asked a million times but i was wondering what is a good rear end posi to install in my 03 interceptor thats going to last and is good for at least 500+hp. And what website i can order one from.
Also what gears to go with...3.73 or 4.10?
Thanks for any and all input

You'll probably want to upgrade to 31 spline axles. You can get those out of 05+ Police interceptors. 3.73s will probably be good and fine.

Are you looking for new or used? Used, I'd check out a mustang forum. Like corral.net New, I'd check out the sponsors section. Just scroll down a little further in the forums page, you'll see it.

Welcome to CVN !

Gears & trac-loc's seem to be very popular mods -

I drove a GM last month with the 2.73 ratio, and it was nowhere near as athletic as the 3.27's in my panther, so I'd guess that 3.73's will make your car seem a lot lighter when you take off.

Put up a pic of your car !

thanks cameronvic

and thanks for the welcome montanaman and info.

im still trying to figure out how to up load one

Put your car info in you signature for now. It makes it easier for people to help with suggestions for your car.

I love my 3:73's but it really depends on your goals for the car..

as for the track loc the FRPP should be able to hold that power just use the carbon clutches..

as stated you can use 31 spline axles out of a 05+ Panther, and you can use a trac loc carrier out for 31 spline out of a 05+ panther or cobra mustang just can't recall what year they went to 31 spline. really just need a 31 spline 8.8 trac loc carrier.

I bought the whole new unit - just so I knew I had everything new - I had the local Ford guru put it in, and the labor was more than the carrier -

http://cgi.ebay.com/ebaymotors/Ford-Raci...sQ5fAccessories

wow awesome website montanaman....buying it right now lol!!!!

While you wait for your new carrier to show up, you'll have time to go find your axles -

Ouch you paid way to much..

You can get a new OEM 8.8 trac-loc 31 spline carrier from Tasca Ford for $117..

new axle? im lost now and not realy mechanicaly inclined. i thought the rear posi was basicaly jus gonna slide right withought having to change or add other equipment to my car.

to upgrade to 31 spline in an 03 you need the 31 spline axles from a 05+ panther and a 31 spline carrier. The carrier is the chunck or piece that the gear set bolts to and the axles slide and loc into the carrier. There are two types of carriers the open and trac-loc units.

if you are swapping out an open carrier for a trac-loc whether 28 spline or 31 spline you would want a pro to install as this requires precise setup.

The axles are easy though and could be done in your driveway.

ok. disregard the last post. decided to stop being lazy and look up some info and i did see how the newer 05+ crownvics have the 31 spline axle but why would i want to upgrade to the 31 spline axle?..Stronger?...last longer?

will the 05+ axle be a direct fit

it is stronger. Your OP stated you wanted something to hold 500hp+.

You don't "have" to upgrade to 31 spine unless you want to. It would be much cheaper if you just upped to a 28 spline track-loc and that would hold plenty. most of the quickest vic on this site I think are still running the 28 spline setup. You could always add a diff girdle to help beef things up. I am still running the 28 spline setup with carbon clutches and girdle. I have no problems. Granted I am not anywhere near the quickest vic on the forum but I could def hold my own

Yes the 05+ would be a direct fit.