Might be too high for towing or big tires but may help with fuel economy for your DD or hwy trips. Sorry… early F350's only.

Ford 10.25 Inch Rear Ring and Pinion F250, F350, F450 Rear End Differential Parts & Service | 10.25 inch Ford Differential ring and pinion set

 

If you use an older (pre 93) ring & pinion in a later housing, don't you just use the older yoke,too?

 

I believe so… that wouldn't affect my '88 I don't think it would need to be changed in the later models but I'm not sure.

I'm just daydreaming about the elusive quest for better 7.5 fuel economy. Right now my truck has 225/75-16's… it came with LT215/85-16's I believe. If I switch to taller LT235/85-16's and change the rear gear from the present 4.10's to a 3.08 I'll lose about 1,000 RPM's @ 62 MPH… from 3,000 RPM's to just over 2,000 according to my p*ss poor math skills. That's got to make a difference in fuel economy.

I got a best of 11.1 coming back from California to Wisconsin last month. When I sold these trucks for a living back in the 90's some of my customers reported about 13-15 hwy economy with 3.55's when they babied the throttle.

I'm sure I'd lose some power when towing but I don't tow everyday and I can live with the occasional drop into 2nd gear (C-6) when pulling a hill. After all I ran up to 20 speed transmissions during my 41 years of trucking and manual shifting was a fact of life. We have pretty much flatlands here anyway and I have been known to get a head start on the hills in my big trucks.

Some early 6.9's had the 3.08's installed from the factory. If I was putting a high gear in a truck with a 302 I wouldn't even think about it... but I have a d*mn 460… it SHOULD be able to do the job!

 

4Lo.com :: Metric Tire Size to Diameter in Inches Calculator

Here's a little sight that will help you calculate all that stuff such as tire size to gear ratio change.

 

Thanks… I have that saved somewhere but forgot all about it.

 

Yea, I save everything but find very little of it when I need it!

 

10-4

 

they used to sell the 3.08 r&p for the sterling 10.25 but i think any of those old ads for them left are all outdated.someone ran into this awhile back.when he called around,no one listing them actually had them to sell.

the c6 is your weakest link.you might want to start on getting the E40D or ZF5 in there before worrying too much about much else.

mid to upper teen hwy peaks is a bit optimistic for much else besides the diesels (but we're paying more in fuel and maintenance,so don't think we have it any better) or the smaller engines in the f150's especially on today's fuel.

460/c6 = yard truck only.no one can afford to run this combo daily anymore man.let's be realistic.you need to find a more modern trans.

 

I'm OK with the C-6… good, strong and reliable. This isn't a daily driver just going to use it for occasional towing duties and hauling my wood heating pellets from a dealer 20 miles away.

I can put a Brownie aux trans o/d behind the C-6… I had one tucked away at a used car dealer's storage yard but some thieves came in and stole a bunch of iron including that trans. Maybe I'll find another.

I could also put in a T-19 with a two speed splitter o/d in front of it… but that stuff is way out of my price range. I can do the gear swap in my shop for under $500.00.

40 years ago I towed my race car with everything from a one ton ex-plumbers truck with a 283/4 speed with 5.13 gears to a Dodge Maxi-van with a 360 and 3.23's and anything in between. A tow rig was anything you had with a trailer hitch on it. Many towed with a station wagon….

Like I said I'm just daydreaming here. I'm not driving this truck yet. It's in my driveway right now waiting it's turn in my shop. But I've owned in about three weeks now and last night I opened the hood for the first time since I drove it home. Just in the planning stages here.

 

To help you with the math, at 62 mph your current setup (29.3" tires, 4.10 gears) gives 2915 rpm.
Changing just the tire size (31.7" tires) gives 2694 rpm.
Changing just the gears (3.08) gives 2190 rpm.
Changing tires and gears gives 2024 rpm.

(Those are all assuming no torque converter slip, so a C6 without a lockup converter will actually put the engine speed a little higher in all cases.)

 

I don't get it.

Why would you have a 1 ton truck and not use it like one but look for better fuel milage.

Sell it and buy a ranger

 

I need a dual purpose vehicle on occasion. If I just needed a work truck i would have kept my Peterbilt and put a 2" ball on it. I'm sure no one else on this board ever drives the dually empty or to the grocery store.

The wife and I like to do the World's Longest Yard Sale on US 127 (Michigan to Alabama) every few years… you miss a lot of bargains if you don't have the room to haul the stuff. Three years ago we used my Ram 1500 but it's a SWB regular cab and this crew cab is just a little roomier.

 

ranger with a 6x12 trailer

Will haul more bulk and till get TWICE the fuel milage

 

Great for the yard sale run but not so great when I need to haul 3 tons of pellets (two tons on the box and one ton in my 6X10 single axle trailer) AND stay legal with the law (not that I'm too worried).


And I can't see hauling my race car behind a 4 banger Ranger although I've hauled heavier cars with 4 door sedans...

 

And 3.08 will suck for hauling ANYTHING other than the EMPTY truck. That is what I am telling you

There is a reason the F350s from 92+ only came with 3.55 and 4.10s