Questions about gears and rear ends help needed

Ok first off what is the difference between my stock 8.8 inch ford rear end and a ford 9 inch?

I have a 95 mercury grand marquis and the stock gears are 2:55's and i want either 3:55 or 3:73

can you give me the pro's and cons on 3:55 and 3:73's?

also how hard is it do drop the new gears in?

how much do they cost?

where would be a good place to get them? ebay? HP motorsports?

Also i want to put true dual exhaust on it also

how hard is that can i cut the y-pipe off and put straight pipes out the back no cats with just dual flow masters or is there another way i should do this?

A couple more questions and im done:
how much does it cost to get heads ported and polished? or is just easier to buy new heads that are already ported/polished

My motor is a 4.6L V-8 SOHC how hard is it to make it a DOHC?

i just want to wake this thing up a little bit and make it sound mean a motha

Any help is appreciated

Thanks,
Mike

Mike,

I will answer what I can.

First off, I would get a trac-loc differential since you probably have an open rear (only one wheel pushing).

I would go with 3.55s. If you get 3.73s and do quite a bit of interstate travel, the vibrations from driveshaft can cause disaster. Get a police interceptor driveshaft and tailshaft if you want to go with gears that steep.

Check out ebay, there are always trac-locs and gears on there.

Check out salvage yards and look for some police interceptors. They come with stainless steel dual exhausts. Any good exhaust/muffler shop should be able to make the appropriate mods to the exhaust.

As for heads, look into getting some Performance Improved heads. They are on the '98 plus Mustangs and '01 plus Crown Vics/Mercs.

Several members have had their PI (Performance Improved) ported by a company called Fox Lake.

Swapping a DOHC motor is expensive and requires fabricating.

Get some ported and polished PI heads, Marauder airbox and MAF, a custom chip, colder spark plugs, 180 thermostat, and some headers. You should see some nice gains with this combo.

If you have not been to www.crownvic.net or www.crownvic.us, then please check them out.

Good luck.

I agree with everything that was said above except the comment on the driveshaft vibrating. The only thing that will make a driveshaft vibrate is it being out of balance. What causes it to go out of balance or vibrate, worn u-joints, broken off balancing weight, dented tube, etc. The gear ratio will not affect the balance. So I would not worry about it. The difference between a 8.8 and a 9", besides the obvious size of the ring gear, the 9" is a stronger differential, the 9" is what is called a front loader because the center section is removable from the front.(makes for easy gear servicing) The 8.8 does not have a removable center section. there are more gear and traction device options available for the 9". If you are only going to "warm over" your engine then the 8.8 will serve you well. The 9" would be a little overkill. It would be smart to get a trac-lock or something equivalent since you will need to get a new carrier anyway because you are jumping up a series size in gear. If you have a overdrive trans(I believe you do) then my choice would be 3.73 gear. No real pros or cons between the two ratios because they are so close in ratio. The gear swap is not real hard but it requires special tools and knowledge to do it right, otherwise they will howl going down the road or have too much play, either way they will wear out in short order.You will want your computer to be recallibrated for the new gear ratio. It wouild be way too costly to try to convert your engine to a DOHC. Cost of the gears? about $150 for the gears themselves, plus the trac-lock about $300, plus bearings, plus labor. I am giving you my best guess on retail prices, not e-bay prices. I hope this helps.