Need advise!!

[Sanford]

I have a 95 F350 4x4 crew cab that I had purchased some years ago. When I purchased the truck it was on 39 inch tires. I have recently lowered it down to 2 inches over stock height on 35 inch tires. Now when I travel on the freeway my RPM'S are between 2200 and 2500 at 60 MPH. I have many questions:
1. How do I figure out my gear ratio without tearing apart the rear end?
2. If I change the gears, what gear ratio should I put in to have my cruising speed be 70 and 75 MPH?
3. Were should I purchase some good quality gears on a budget? (I would even consider used ones)
4. Any recommendations on a place to install the gears on a budget?
5. What did this year's truck have as a factory gear ratio, and what was the average RPM at 60 MPH?

Thanks for the advise in advance!

[optx002]

I think your truck should have come with 3.73. It probably has 4.56 right now or maybe even 4.88 but i dont know for sure.

If you tow alot, 4.10's or 4.30's would be good. I had 35's with 3.73s and it felt ok but wasnt great for towing. If your just doing alot of empty cruising. stock 3.73 or 4.10's would be good.

Hoopers rear end exchange in Sun Valley does good work and are fairly reasonably priced.

[K5Cruiser]

I tried to look where I posted it before but couldn't find it. Anyway, if you want to determine what gear you have now, you can obviously pull the diff cover, count the teeth on the ring and pinion and do the calculation to figure out the ratio. If you don't want to get dirty and change the fluid, then you can raise up the rear end of your vehicle and count the number of rotations your driveshaft turns for every full turn of your rear wheel. It's best to mark the driveshaft with some tape or paint so that you can see it turning. For example if your driveshaft turns just over four times to your rear wheel turning one full turn, you've got a 4.10 gear ratio.

Do a google search for "gear ratio calculator" and there are all kinds of sites that will come up where you can input the information on your truck and find out various information. You can change the gear ratio, speed, tire height, rpm, basically any of the factors that effect what gear ratio you end up with. This is just one example... http://www.4lo.com/calc/gearratio.htm

As Jay indicated above, Hoopers has always had good reviews and is the only place I would recommend. It's a little bit out of your way, but worth it to get it done right the first time.

[Ftreefitty]

You can see what was put in originally if that helps from the VIN decal at the drivers door and theres a little metal tag on the differentials that has some numbers on it that a ford parts counter guy who has the decoder ring could tell you.

[Sanford]

Hey thanks for the replys. I removed the rear diff cover and counted gears, turns out I have 456. If I went with 410 does anyone know what that would put the rpms at about 70 mph with 35" tires? And for the record, I know advice is spelled with a c. I had someone start this post for me when I was at work.

[K5Cruiser]

Assuming you have an E4OD or 4R100 transmission, and if my quick internet search is correct, that tranny has a 0.71 4th gear ratio. Plugging that into the computer at the link I attached above, along with 35" tires at 70mph and 4.56:1 gears, you get 2182rpm.