7.3 diesel with 355 gears

I think this is what I had in 2000 F250. Was pulling 15k trailers on overdrive just fine.
It was 4WD, so in case of need for low gear I could switch to LOW, but beside going into dirt, I don't recall need for it.
RPM comparison is straight math. Ask your grandson ;)

Lower numerical gears, ie going to 3.54 from 4.-0, is gearing higher.
I had the same situation with my 4.10 ‘99 Dodge dually.
I put in a Gear Vendors overdrive, so I still have my 4.10s for when I’m heavy but I hit the button and it’s 3.20. My 60 MPH RPM goes from a bit under 2000 down to a bit under 1500.

If your truck is 4WD the cost is similar. If you have 2WD and only have to change out the rear differential, it’s a lot cheaper to re-gear.

If you consider the overdrive, pay no attention to Gear Vendors wild claims of MPG improvements. It won’t make much difference at all, not will it ever pay for itself.
It does make the truck a lot more pleasant to drive. You’re not always wanting to shift up one more time like you do with 4.10 gears. That’s what you buy it for.

Contrary to one of the replies here, if you're talking about a healthy 95 7.3 diesel, it's anemic in stock form. It should have just enough to haul a TC ok with higher gears, but it will be a bigger dog than it is now.
I'd keep the 4.10s unless you're looking for empty freeway driving manners to be better.
For future reference, don't believe any claims of towing 15klbs in overdrive with your truck, except maybe downhill.
Depends how much you want to sink into a truck compared to what its worth.

djg wrote:
Has anyone had 355 gears with a 7.3 diesel was thinking about changing to them from 410's but want to know if it will be geared too low, also what rpm will 65mph, be at 410's at 1900 is about 56mph

Is your 7.3 stock or chipped at all? We pull a 12,000# 5er with a CTD with RV275 injectors and a small 50 HP chipfigure about 300 HP and 610 TQ.

Your total weight should not exceed about 14K we tow at about 20K.

My 7.3 is stock tune with a banks on it, runs exceptional just tired of 55 to 57mph to keep fuel mileage decent at 60mph I'm running 2000rpm and fuel milage drops so that has been my thinking on changing gears

Isn't that drop in mileage more a result of increased wind resistance which increases as the square of the velocity? If so, then it doesn't matter what gears you have. You'll need to add the same amount of power to overcome the resistance at 60 mph.

The only reason I mention this is due to an experiment that was forced upon me. I had belt sep in the 2 rear tires on one of my cars. I had to wait 4 days to get new tires and in that 4 days I was driving about 55 MPH everywhere (instead of my usual 9 over the speed limit lol). I noticed that average gas mileage took a 25% jump. Nothing else changed except velocity.

Just something to ponder.

djg wrote:
My 7.3 is stock tune with a banks on it, runs exceptional just tired of 55 to 57mph to keep fuel mileage decent at 60mph I'm running 2000rpm and fuel milage drops so that has been my thinking on changing gears

Stock fueling and a Banks what? Exhaust, turbo, intercooler, bumper sticker?

Question is power and speed vs mileage. Gearing helps to an extent, but IMO not as much as you think. Now, are you running out of comfortable rpms at your intended speed? Do you want to just drive 60 mph giver take? If so keep the gears and the power they afford you.
You won't pay back mileage increase due to gears in a lot of miles. That would be the last reason to re gear IMO.

If you want a little rpm decrease, upsize the tires next time around.
You need to balance how much power to spare you have now with cutting the gearing by that much. And does your Trans have enough gears and the right ratio to support those new higher gears at your intended speed?
2000rpms isn't _____. Sounds like the low end of operating range for a 7.3 if you're not just empty cruising. What will that do to your (4 or 5 speed) trans?

Grit dog it has an intercooler on it and that was what I was thinking about the gears going to 355's too much loss, I was also thinking about a tire change next time though as I only have 16's on it now but won't the increased tire height loose fuel milage I hear 1 MPG per 1" of lift can't say for sure though just what I have heard

Well the Gear Vendors would give you both worlds. Pulling gears and freeway gears.
There’s no hard rule that x tire size will change your mileage y amount.
There are too many variables.
If you lack power, that can be fixed. The 7.3 is a great motor and it’s not hard to bump it up a little to a more acceptable level without going too wild. I’ve driven some slightly modded 7.3s that were absolute stompers, and reliable everyday.

I also believe the better MPG at the slower speed has everything to do with drag and almost nothing to do with the slight engine RPM change.
It’s pretty well known that trucks with campers will get a lot better mileage if you slow down somewhere in the 50s for MPH vs. 60+.

I have the 7.3 with 355 gears and 5 speed stick shift. Been all over the USA hauling a 9.5 ft. camper with no problems. My previous truck had the 410 gearing and when I ordered the 7.3 I went with the 355 gearing for a quieter ride. Unless you are pulling a big 5er you don't need the 410.