Engine/Transmission (1998.5 - 2002) 410 Rear End to a 355???

[ASharp]

I have a 2000 6sp with a 410. I will use this truck 90% on the intersate and wow 2500 rpm at 75 mph for 4 hours gets a bit annoying.



Couple of ?'s

1-If I go to a 355 at 75mph what should my rpms be?

2-Other than changing the front and rear diffs out is there anything else that has to be done?



Thanks in advance!

 

[DCreed]

read cost of diff ratio change in this catagory.

 

[ASharp]

DCreed

I read the article and am still wondering what my RPM would be lowered to if I made the swap. It seems that all I would need to do is swap out the 2.

 

[BWagnaar]

Here check this site out: Calulators from www.4Lo.com

According to them if you had 31" tires, 3. 55 gears, 4th gear ratio of . 69, and doing 75mph... . You'd be doing about 1991 RPMs.

 

[Dave Ratcliffe]

The 6 speed has a 0. 73 overdrive, so with 31. 5" tires (265/75R16s) you'll be right at 2,070 rpms at 75mph.

 

[hdtrukn]

Might be easy to change tires.

2 inch taller lowers RPM by 200.

Just did it on my dually. 235/85/16 to 245/85/16

 

[24Vpirate]

i did it to mine with 285/75/16 75mph is 1950 rpm definitly worth it

 

[Brand-X]

i did it to mine with 285/75/16 75mph is 1950 rpm definitly worth it

Is this with 4. 10 gear thanks George

 

[GCULP]

I don't know about the cost, but there is a guy on here with 3. 55's that is looking to go the other way, you might work out a trade. check the link below



https://www.turbodieselregister.com...998-5-2002/183066-cost-diff-ratio-change.html

 

[ASharp]

I am starting to think that keeping the 410's is best. Maybe swapping tires, since they need it anyway, would be best.



thoughts?

 

[Mhannink]

swap gears the higher gear ratio will be easier for the motor to turn then bigger tires

 

[CumminsPower98]

The 6 speed has a 0. 73 overdrive, so with 31. 5" tires (265/75R16s) you'll be right at 2,070 rpms at 75mph.

This isn't quite accurate. My truck: NV5600, 3. 54 gears, 265/75/16 tires. 2k rpm =70 on the dot. I have a true speed correction box and it's accurate to within a mile on a full 700+ mile trip, which happens almost daily.

 

[ASharp]

CumminsPower98

What RPm's are you turnning at 75mph. I am at 2500

 

[CumminsPower98]

I'm not sure as I don't go 75 a lot for mileage and noise reasons. I think it's something pretty close to 2250 but it could be slightly less then that too.

 

[dpuckett]

If you're going 70 @ 2000RPM, then you will turn about 2150 at 75, which is a hair less than the 2200 @ 75 I turn in my 3. 54 truck with a . 77 OD ratio.



Daniel

 

[CCahill]

Don't forget these tach's are not in increments of 100... they are more like 125 for each tick mark...

 

[ASharp]

Ok, I have now made the decision to change gears. My 410's are driving me nuts on the highway. Anyone want to swap for my 410's? I have a 2000 2500 4x4 6sp



Would like 354's



Anyone know the cost for the labor and parts to swap out the gears? what else is needed(parts) other than the gears themself?