I will try to keep it short. I have a 00 V10 Excursion, geared 4.89 with 38 tires. I bought a newer 6.0 Excursion to replace it. I have very little experience with diesels and only have run the new one for a couple hundred miles. It has slightly oversized tires on it now, 32.7 tall, stock is 31.6, with 3.73 gearing. My plan is to swap axles (front has custom bracketry on it for a 4-link) and suspension from one to the other. The problem lies in the gearing. I have either stock 3.73 or the 4.89. One too low, one too high.

According to calculators, the tire I would need with 4.89 gears to equal the stock ratio would be a 41. I was thinking of going to a 40 anyway, which would be pretty close to stock gearing with the 4.89 gears.
I really don't want to regear axles again, I just did it and hated it.

SO I guess the question is, would 40's, being slightly undergeared with 4.89, considering the extra weight of the tires/wheels, how tall the truck is for wind reisistance/etc., be the best choice? I do pull a 4 place snogo trailer, 5000 pounds max usually. But would like to be able to put my off road Explorer in it once in a while, so weight would be closer to 7500 pounds.

I know the limitations of the 6.0, and will be doing a mild tune on it also, with guages and exhaust. It doesn't seem to have a ton of torque off the line as it is, so being geared high seems like it might be miserable to drive.

Rambling. Any thoughts?

 

Not a big deal,p I would want the slightly lower gearing for empty all round mpg. Pulling the snow trailer, you keep 40's on it? Round here we go to skinny winter rated tires, roads are terrible pulling a trailer with 40's. I might be inclined to leave the 3.73 and go as high as a 35 inch tire you can run all year?

 

I'd leave the axles alone. You'll be removing the Dana 60 front from the newer rig to swap in a Dana 50... 3.73 is fine for mildly larger tires, up to 35" should be okay with proper tuning.

 

Gas engines react differently than diesel do to daily driving. My F250 is a bit of a dog around town, it is not a stop-light monster by any means. My Ram 2500 hemi with a 5 speed manual trans is a total hot-rod in comparison, and third gear around 50 - 60 mph is a real hoot... But get a load on, on a highway, and the difference is astounding. The F250 pulls a load on a road in fifth gear with ease that the 2500 Hemi was full throttle in 4th gear to keep up to the speed limit, if it could keep up... And gets more than 50% better fuel mileage doing it.

Factory put all sorts of different wheels and tires on stock, all with the 3.73 diff ratio. I wouldn't worry about gearing too much. If anything I would over-gear it a bit (lower numerical ratio). You don't pull a heavy load with it. OTOH, I wouldn't swap axles either.

Brian

 

Will either keep the 38s I have on the V10 version now or go 40's if I can find a decent deal. Honestly, I want the 40's, and keep my geared axles, that would be the easiest/quickest. Easy suspension swap except for all of the 4 link brackets that have to be transferred. Plus my rear end has a limited slip, the new one doesn't.
Roads here are good year round, almost never have snow or ice, they plow/calcium chloride the heck out of them. We get a ton of snow, just not on the roads, I ran 13.5 wide 39's all winter, they did great.

 

Excurisons don't have Dana 60s.

 

I did notice that with mine, far from a hot rod off the line, but good once it gets spooled up. And with a trailer, almost NO difference, I did like seeing that.

 

What year Ex is it? Is it leaf spring front? What lift will you do to clear the 40" tires?

Brian

 

I have a 00 V10 and an 04 Dielsel. Exes never got the coilver front end. I have a custom 4-link setup on the front, with Fox coilovers.